IMac mid 2007 Runs Slow on Yosemite, unresponsive

Question

PLEASE CAN YOU ADVISE:
I have been visiting my Dad and two days later his computer (it seemed after a power cut) now RUNS VERY slow, it is unresponsive when clicking on any application on the menu bar, or even the finder bar, it shows spinning ball. I read your forum and will paste the Etrecheck results here. He has tried the pram thing on startup but still no good. He has iMac 20 inch Mid 2007. Yosemite 10.10.2., 2.4 Ghz Intel Core 2Duo, mem 2 Gb 667 Mhz DDR2 Sdram. Startup disk iMac, Graphics ATI Radeon HD 2600 Pro 256mb.
Report from Etrecheck.
EtreCheck version: 1.9.15 (52)
Report generated February 21, 2015 at 11:10:48 AM EST
Hardware Information: ?
    iMac (20-inch, Mid 2007) (Verified)
    iMac - model: iMac7,1
    1 2.4 GHz Intel Core 2 Duo CPU: 2 cores
    2 GB RAM
Video Information: ?
    ATI,RadeonHD2600 - VRAM: 256 MB
        iMac 1680 x 1050
System Software: ?
    OS X 10.10.2 (14C109) - Uptime: 0 days 1:3:1
Disk Information: ?
    Hitachi HDT725032VLA360 disk0 : (320.07 GB)
    S.M.A.R.T. Status: Verified
        EFI (disk0s1) <not mounted>: 209.7 MB
        lMAC (disk0s2) / [Startup]: 319.21 GB (189.2 GB free)
        Recovery HD (disk0s3) <not mounted>: 650 MB
USB Information: ?
    Apple, Inc. Keyboard Hub
        Apple, Inc Apple Keyboard
    Apple Inc. Built-in iSight
    Elgato EyeTV Hybrid
    Logitech USB Receiver
    Apple Inc. Bluetooth USB Host Controller
    Apple Computer, Inc. IR Receiver
Gatekeeper: ?
    Mac App Store and identified developers
Kernel Extensions: ?
    [loaded]    com.Cycling74.driver.Soundflower (1.5.1) Support
    [loaded]    com.Logitech.Control Center.HID Driver (3.9.1 - SDK 10.8) Support
    [not loaded]    com.Logitech.Unifying.HID Driver (1.3.0 - SDK 10.6) Support
    [not loaded]    com.bresink.driver.BRESINKx86Monitoring (9.0) Support
    [not loaded]    com.elgato.driver.DontMatchAfaTech (1.1) Support
    [not loaded]    com.elgato.driver.DontMatchCinergy450 (1.1) Support
    [not loaded]    com.elgato.driver.DontMatchCinergyXS (1.1) Support
    [not loaded]    com.elgato.driver.DontMatchEmpia (1.1) Support
    [not loaded]    com.elgato.driver.DontMatchVoyager (1.1) Support
    [loaded]    com.intego.kext.AppBarrierKPI (2.2) Support
    [loaded]    com.intego.kext.ContentBarrierBootTime (10.5.5 ) Support
    [loaded]    com.intego.kext.NetBarrierKPI (10.5.4) Support
    [not loaded]    com.olympus.CamBlockCommandsDeviceUP (1.0.0) Support
    [not loaded]    com.symantec.kext.SymAPComm (11.0.0) Support
    [not loaded]    com.symantec.kext.ips (1.2f28) Support
Startup Items: ?
    Cocktail: Path: /Library/StartupItems/Cocktail
Problem System Launch Daemons: ?
    [failed]    com.apple.awdd.plist
    [failed]    com.apple.cache_delete.plist
    [failed]    com.apple.coresymbolicationd.plist
    [failed]    com.apple.ctkd.plist
    [failed]    com.apple.findmymac.plist
    [failed]    com.apple.iconservices.iconservicesagent.plist
    [failed]    com.apple.iconservices.iconservicesd.plist
    [failed]    com.apple.ifdreader.plist
    [failed]    com.apple.MobileFileIntegrity.plist
    [failed]    com.apple.nehelper.plist
    [failed]    com.apple.nsurlsessiond.plist
    [failed]    com.apple.sandboxd.plist
    [failed]    com.apple.softwareupdated.plist
    [failed]    com.apple.spindump.plist
    [failed]    com.apple.sysmond.plist
    [failed]    com.apple.tccd.system.plist
    [failed]    com.apple.wdhelper.plist
Problem System Launch Agents: ?
    [failed]    com.apple.accountsd.plist
    [failed]    com.apple.AirPlayUIAgent.plist
    [failed]    com.apple.bird.plist
    [failed]    com.apple.CallHistoryPluginHelper.plist
    [failed]    com.apple.CallHistorySyncHelper.plist
    [failed]    com.apple.cloudd.plist
    [failed]    com.apple.coreservices.appleid.authentication.plist
    [failed]    com.apple.coreservices.uiagent.plist
    [failed]    com.apple.icloud.fmfd.plist
    [failed]    com.apple.iconservices.iconservicesagent.plist
    [failed]    com.apple.nsurlsessiond.plist
    [failed]    com.apple.pbs.plist
    [failed]    com.apple.pluginkit.pkd.plist
    [failed]    com.apple.secd.plist
    [failed]    com.apple.security.cloudkeychainproxy.plist
    [failed]    com.apple.spindump_agent.plist
    [failed]    com.apple.telephonyutilities.callservicesd.plist
Launch Daemons: ?
    [running]    com.adobe.fpsaud.plist Support
    [running]    com.arcsoft.eservutil.plist Support
    [loaded]    com.google.keystone.daemon.plist Support
    [running]    com.intego.BackupAssistant.daemon.plist Support
    [running]    com.intego.commonservices.daemon.plist Support
    [running]    com.intego.ContentBarrierX5.daemon.plist Support
    [running]    com.intego.netbarrier.daemon.plist Support
    [running]    com.intego.personalantispam.daemon.plist Support
    [running]    com.intego.task.manager.daemon.plist Support
    [failed]    com.intego.VirusBarrier.daemon.plist Support
    [failed]    com.intego.VirusBarrier.logger.daemon.plist Support
    [failed]    com.intego.VirusBarrier.scanner.daemon.plist Support
    [running]    com.magican.castle.plist Support
    [not loaded]    com.maintain.AutoLoginUserScreenLocked.plist Support
    [not loaded]    com.maintain.HideSpotlightMenuBarIcon.plist Support
    [running]    com.micromat.TechToolProDaemon.plist Support
    [loaded]    com.oracle.java.Helper-Tool.plist Support
    [loaded]    com.oracle.java.JavaUpdateHelper.plist Support
    [running]    com.perion.searchprotectd.plist Support
    [loaded]    com.stclairsoft.DefaultFolderXAgent.plist Support
    [loaded]    com.symantec.avscandaemon.plist Support
    [loaded]    com.symantec.diskMountNotify.plist Support
    [loaded]    com.symantec.MissedTasks.plist Support
    [loaded]    com.symantec.navapd.plist Support
    [loaded]    com.symantec.Sched501-1.plist Support
    [running]    com.symantec.symdaemon.plist Support
    [running]    com.symantec.symSchedDaemon.plist Support
    [loaded]    com.symantec.uiagent.plist Support
    [running]    com.zeobit.MacKeeper.plugin.AntiTheft.daemon.plist Support
Launch Agents: ?
    [running]    com.arcsoft.esinter.plist Support
    [loaded]    com.divx.dms.agent.plist Support
    [loaded]    com.divx.update.agent.plist Support
    [running]    com.epson.epw.agent.plist Support
    [loaded]    com.google.keystone.agent.plist Support
    [loaded]    com.hp.help.tocgenerator.plist Support
    [loaded]    com.intego.backupassistant.agent.plist Support
    [running]    com.intego.ContentBarrierX5.agent.plist Support
    [loaded]    com.intego.netbarrier.alert.plist Support
    [running]    com.intego.netupdate.agent.plist Support
    [loaded]    com.intego.task.manager.notifier.plist Support
    [loaded]    com.intego.VirusBarrier.alert.plist Support
    [running]    com.Logitech.Control Center.Daemon.plist Support
    [not loaded]    com.maintain.LogOut.plist Support
    [loaded]    com.maintain.PurgeInactiveMemory.plist Support
    [not loaded]    com.maintain.Restart.plist Support
    [not loaded]    com.maintain.ShutDown.plist Support
    [not loaded]    com.maintain.Sleep.plist Support
    [running]    com.maintain.SystemEvents.plist Support
    [running]    com.micromat.TechToolProAgent.plist Support
    [loaded]    com.oracle.java.Java-Updater.plist Support
    [running]    net.culater.SIMBL.Agent.plist Support
User Launch Agents: ?
    [loaded]    com.adobe.ARM.[...].plist Support
    [running]    com.coppertino.VoxHelper.plist Support
    [loaded]    com.genieo.completer.download.plist Support
    [loaded]    com.genieo.completer.ltvbit.plist Support
    [running]    com.genieo.completer.update.plist Support
    [running]    com.plexapp.mediaserver.plist Support
    [running]    com.victorpimentel.TVShowsHelper.plist Support
    [running]    com.zeobit.MacKeeper.Helper.plist Support
User Login Items: ?
    GrowlMenu
    Skype
    Default Folder X Helper
    My Day
    EyeTV Helper
    iDVD
    Antispam Engine
    WashingMachineHelper
    Quicken Scheduler
    Dropbox
    Alfred 2
    Launch Nikon Message Center 2
    Mac Game Store Helper
    MacUpdate Desktop
    MacUpdate Desktop 2
    MacUpdate Desktop
    MacUpdate Desktop 4
    DragThing
    MacUpdate Desktop 3
    Launch Nikon Message Center 2
Internet Plug-ins: ?
    AdobePDFViewerNPAPI: Version: 11.0.10 - SDK 10.6 Support
    Flash Player: Version: 16.0.0.305 - SDK 10.6 Support
    DivX Web Player: Version: 3.2.4.1250 - SDK 10.6 Support
    LogMeInSafari32: Version: 1.0.979 - SDK 10.7 Support
    AdobePDFViewer: Version: 11.0.10 - SDK 10.6 Support
    iPhotoPhotocast: Version: 7.0
    RealPlayer Plugin: Version: (null) Support
    PDEPrint: Version: 2.0 Support
    DirectorShockwave: Version: 12.1.0r150 - SDK 10.6 Support
    PDF Browser Plugin: Version: 2.4.4 - SDK 10.6 Support
    FlashPlayer-10.6: Version: 16.0.0.305 - SDK 10.6 Support
    QuickTime Plugin: Version: 7.7.3
    PandoWebInst: Version: 1.0 Support
    Silverlight: Version: 5.1.30514.0 - SDK 10.6 Support
    OVSHelper: Version: 1.1 Support
    LogMeIn: Version: 1.0.979 - SDK 10.7 Support
    Google Earth Web Plug-in: Version: 6.1 Support
    Default Browser: Version: 600 - SDK 10.10
    Flip4Mac WMV Plugin: Version: 3.3.2.18   - SDK 10.7 Support
    SlingPlayer: Version: (null) - SDK 10.8 Support
    JavaAppletPlugin: Version: Java 8 Update 31 Check version
    OfficeLiveBrowserPlugin: Version: 12.3.6 Support
Safari Extensions: ?
    searchExt-1
Audio Plug-ins: ?
    BluetoothAudioPlugIn: Version: 4.3.2 - SDK 10.10
    AirPlay: Version: 2.0 - SDK 10.10
    AppleAVBAudio: Version: 303.1 - SDK 10.10
    iSightAudio: Version: 7.7.3 - SDK 10.10
iTunes Plug-ins: ?
    Quartz Composer Visualizer: Version: 1.5 - SDK 10.10
User Internet Plug-ins ?
    TroviNPAPIPlugin: Version: 1.0 - SDK 10.9 Support
    Picasa: Version: 1.0 - SDK 10.4 Support
    Google Earth Web Plug-in: Version: 7.1 Support
3rd Party Preference Panes: ?
    Default Folder X  Support
    Flash Player  Support
    Flip4Mac WMV  Support
    Growl  Support
    Java  Support
    Logitech Control Center  Support
    MenuMeters  Support
    NetUpdate  Support
    Norton\nQuickMenu  Support
    Perian  Support
    Quicktime X Preferences  Support
    TechTool Protection  Support
    TVShows  Support
    Vox Preferences  Support
Time Machine: ?
    Time Machine not configured!
Top Processes by CPU: ?
        15%    InstallerS
         2%    WindowServer
         2%    cloudd
         1%    Microsoft Entourage
         1%    iDVD
Top Processes by Memory: ?
    75 MB    InstallerS
    49 MB    Skype
    43 MB    AddressBookSourceSync
    39 MB    cloudd
    39 MB    com.apple.internetaccounts
Virtual Memory Information: ?
    31 MB    Free RAM
    382 MB    Active RAM
    347 MB    Inactive RAM
    378 MB    Wired RAM
    5.37 GB    Page-ins
    197 MB    Page-outs

Answer 1

Given the circumstances I agree taking it to an Apple Store might be the best way to address the problems with it. Manually eradicating all the software contributing to its unacceptable performance will be time-consuming and tedious. If it were mine there is no question I'd erase it and reconfigure it from the ground up. That would be less time-consuming and more likely to be successful, but it's also tedious.
And I do agree with a previous respondent that he could use some more RAM.
So do I. 2 GB is the absolute minimum for Yosemite to even run, and it won't run well with that little. That Mac can address as much as 6 GB, which would probably be acceptable if you were to reconfigure it and leave out the garbage software causing and / or contributing to poor performance.
Lastly, you have to evaluate how much time and money you are willing to spend on a Mac that's nearly eight years old. Age itself doesn't kill Macs, but eight years is about as much economic life that can be expected from any computer. Among the limitations that cannot be overcome are its Core 2 Duo CPU and RAM. Even 6 GB memory isn't all that much any more.
Having said that, even a brand new fully configured top of the line Mac Pro would run poorly, if at all, given the software that's on your Dad's Mac. Intego, Norton/Symantec, MacKeeper, Cocktail... all that stuff is utter garbage and there is too much of it to mention. Personal testing of Intego alone on a brand new Mac containing nothing other than one minimally configured user account resulted in performance degradation so extreme no knowledgeable Mac user would consider it acceptable.
For reference, here is the procedure I would recommend:
Back up your Mac if you have not already done so. To learn how to do that read Mac Basics: Time Machine backs up your Mac. You will need a suitable external hard disk drive for this purpose. One with adequate capacity can be purchased for about $60.
The recovery procedure will require that you erase the Mac using OS X Recovery, and then create a new user whose contents will be empty. You will then be able to use Setup Assistant to migrate your essential documents including photos, music, work products and other essential files.
When doing so, select only your previous User account and do not select "Applications", "Computer and Network Settings" or "Other files and folders". De-select those choices.
Subsequent to using Setup Assistant, you will need to reinstall the essential software you may require, once again remembering to install software only from their original sources, and omitting all non-essential software.
Always obtain software from authorized sources such as the Mac App Store, original installation media (CD or DVD), or from the developer's authorized download source. Never obtain software from download aggregator websites such as C net dot com, Mac Update dot com, Soft onic dot com, random popups that may appear while browsing the Internet, or other sources that primarily rely upon junk product advertisements for their revenue. Such sites are not to be trusted, and are the most common means of distributing adware or other junk you probably do not want.
To erase and install Yosemite read: OS X Yosemite: Erase and reinstall OS X
To migrate your essential documents read: OS X Yosemite: Transfer your info from a computer or storage device and follow the procedure under Transfer info from a Time Machine backup or other storage device.