My Very Slow Mid-2007 iMac

Question

My iMac was running unbearably slow. I'm not just talking slow to load a web page; I'm talking slow as in 20-30 second waits simply to get a drop-down menu to open or to save a file and 15 to 20 minutes to initially boot. I followed suggestions that I found in forums online, running Repair Disk Permissions and Repair Disk, for example. The latter helped for a time but became less and less effective for shorter intervals. I installed OSX Yosemite 10.1, hoping that would help. It did not.
At one point I came across a suggestion to run Activity Monitor. Running AM showed a recurring message: Google Chrome Helper not responding. Further checking seemed to indicate that this was a minor bug and would not affect performance. Nevertheless, I tried to disable Chrome Helper, following the directions in a post. I also installed a beta version of Chrome that was supposed to address the bug. The situation did not improve. I tried running Safari. I had similar issues with Safari.
On a whim, I downloaded the latest version of Firefox. I used to use Firefox but switched to Chrome when my school system started using Google Apps and suggested that Chrome would be the best choice of browser to work with Google Apps. When I opened Firefox, the problems almost totally disappeared. Web pages load instantly, and I am no longer getting the annoying spinning pinwheel when I click on a drop down menu. I am not a technical person so I have no idea why this should be happening or if my success will last. There seems to be no logic to it. Nevertheless, I am posting this in the event that it might help someone else going through the frustration of watching the interminably spinning rainbow wheel.
Nice Name: iMac 24 inch Core 2 Duo Aluminium (Mid 2007)
Machine Model: iMac7,1
Name: iMac Intel (mid 2007)
ModelCode: imac_mid_07
Family name: A1225
Model Number: MB322
Group1: iMac
Group2: Intel
Generation: 4
CPU speed: 2.8GHz
Screen size: 24 inch
Screen resolution: 1920x1200 pixels
Colour: Aluminium
Production year: 2007
Production week: 51 (December)
Production number: 343 (within this week)
Model introduced: 2007
Memory - flavour: DDR2-S-667
Memory - number of slots: 2
Memory - maximum total: 6GB
Memory - largest module: 4GB
Factory: QP (USA)

Answer 1

Hi, I have almost the same imac than the OP with macOS 10.1 Yosemite installed. Is very slow. I ran ETreCheck but don't know how to interpret it. Can anyone help?
EtreCheck version: 2.1.5 (108)
Report generated 10 de enero de 2015, 13:19:16 CET
Click the [Support] links for help with non-Apple products.
Click the [Details] links for more information about that line.
Click the [Adware] links for help removing adware.
Hardware Information: ℹ️
  iMac (24-inch Mid 2007) (Verified)
  iMac - model: iMac7,1
  1 2.8 GHz Intel Core 2 Duo CPU: 2-core
  4 GB RAM Upgradeable
  BANK 0/DIMM0
  2 GB DDR2 SDRAM 667 MHz ok
  BANK 1/DIMM1
  2 GB DDR2 SDRAM 667 MHz ok
  Bluetooth: Old - Handoff/Airdrop2 not supported
  Wireless:  en1: 802.11 a/b/g/n
Video Information: ℹ️
  ATI,RadeonHD2600 - VRAM: 256 MB
  iMac 1920 x 1200
System Software: ℹ️
  OS X 10.10.1 (14B25) - Uptime: 2 days 3:14:59
Disk Information: ℹ️
  ST3500630AS Q disk0 : (500,11 GB)
  EFI (disk0s1) <not mounted> : 210 MB
  Macintosh HD (disk0s2) / : 465.35 GB (193.25 GB free)
  Recovery HD (disk0s3) <not mounted>  [Recovery]: 650 MB
  NO NAME (disk0s4) /Volumes/NO NAME : 33.89 GB (29.17 GB free)
USB Information: ℹ️
  Western Digital My Passport 07B8 1 TB
  EFI (disk1s1) <not mounted> : 210 MB
  My Passport for Mac (disk1s2) /Volumes/My Passport for Mac : 999.83 GB (904.37 GB free)
  Apple Inc. Built-in iSight
  TASCAM US-122L
  Apple Inc. Bluetooth USB Host Controller
  Apple Computer, Inc. IR Receiver
Gatekeeper: ℹ️
  Anywhere
Kernel Extensions: ℹ️
  /Incompatible Software/Parallels Service.app
  [not loaded] com.parallels.kext.prl_hid_hook (5.0 9308.543614) [Support]
  [not loaded] com.parallels.kext.prl_hypervisor (5.0 9308.543614) [Support]
  [not loaded] com.parallels.kext.prl_netbridge (5.0 9308.543614) [Support]
  [not loaded] com.parallels.kext.prl_usb_connect (5.0 9308.543614) [Support]
  [not loaded] com.parallels.kext.prl_vnic (5.0 9308.543614) [Support]
  /Library/Extensions
  [not loaded] foo.tap (1.0) [Support]
  [not loaded] foo.tun (1.0) [Support]
  /System/Library/Extensions
  [loaded] com.Cycling74.driver.WondershareAudioDevice (1.5.2) [Support]
  [loaded] com.logmein.driver.LogMeInSoundDriver (4.1.46f67) [Support]
  [loaded] com.rim.driver.BlackBerryUSBDriverInt (0.0.64) [Support]
  [loaded] com.tascam.usb2audio.driver (1.13.4) [Support]
  [loaded] com.vara.driver.VaraAudio (1.0.3) [Support]
  /System/Library/Extensions/TASCAM_US1xx.kext/Contents/PlugIns
  [not loaded] com.tascam.usb2audio.driver_TIGER (2.10.4 - SDK 10.4) [Support]
Startup Items: ℹ️
  DynDNSUpdater: Path: /Library/StartupItems/DynDNSUpdater
  ParallelsDesktopTransporter: Path: /Library/StartupItems/ParallelsDesktopTransporter
  ParallelsTransporter: Path: /Library/StartupItems/ParallelsTransporter
  tap: Path: /Library/StartupItems/tap
  tun: Path: /Library/StartupItems/tun
  Startup items are obsolete in OS X Yosemite
Problem System Launch Agents: ℹ️
  [killed] com.apple.CallHistoryPluginHelper.plist
  [killed] com.apple.CallHistorySyncHelper.plist
  [killed] com.apple.coreservices.appleid.authentication.plist
  [killed] com.apple.icloud.fmfd.plist
  [killed] com.apple.printtool.agent.plist
  [killed] com.apple.telephonyutilities.callservicesd.plist
  6 processes killed due to memory pressure
Problem System Launch Daemons: ℹ️
  [killed] com.apple.AssetCacheLocatorService.plist
  [killed] com.apple.awdd.plist
  [killed] com.apple.ctkd.plist
  [killed] com.apple.GSSCred.plist
  [killed] com.apple.icloud.findmydeviced.plist
  [killed] com.apple.ifdreader.plist
  [killed] com.apple.nehelper.plist
  [killed] com.apple.tccd.system.plist
  [killed] com.apple.wdhelper.plist
  9 processes killed due to memory pressure
Launch Agents: ℹ️
  [loaded] com.google.keystone.agent.plist [Support]
  [invalid?] com.logmein.LMILaunchAgentFixer.plist [Support]
  [running] com.logmein.logmeingui.plist [Support]
  [running] com.logmein.logmeinguiagent.plist [Support]
  [not loaded] com.logmein.logmeinguiagentatlogin.plist [Support]
  [loaded] com.oracle.java.Java-Updater.plist [Support]
  [running] com.pianomarvel.plugin.plist [Support]
  [running] com.rim.BBLaunchAgent.plist [Support]
  [running] com.wondershare.AllMyMusic.Agent.plist [Support]
Launch Daemons: ℹ️
  [loaded] com.adobe.fpsaud.plist [Support]
  [running] com.fitbit.galileod.plist [Support]
  [loaded] com.google.keystone.daemon.plist [Support]
  [running] com.logmein.logmeinserver.plist [Support]
  [invalid?] com.logmein.raupdate.plist [Support]
  [loaded] com.oracle.java.Helper-Tool.plist [Support]
  [running] com.rim.BBDaemon.plist [Support]
  [loaded] com.timesoftware.timemachineeditor.backupd-auto.plist [Support]
  [running] org.samba.nmbd.plist [Support]
  [running] org.samba.smbd.plist [Support]
User Launch Agents: ℹ️
  [loaded] com.adobe.ARM.[...].plist [Support]
  [running] com.spotify.webhelper.plist [Support]
User Login Items: ℹ️
  WDDriveUtilityHelper Aplicación (/Applications/WD Drive Utilities.app/Contents/WDDriveUtilityHelper.app)
Internet Plug-ins: ℹ️
  Default Browser: Version: 600 - SDK 10.10
  Flip4Mac WMV Plugin: Version: 2.4.0.11 [Support]
  AdobePDFViewerNPAPI: Version: 11.0.07 - SDK 10.6 [Support]
  FlashPlayer-10.6: Version: 16.0.0.235 - SDK 10.6 [Support]
  DivXBrowserPlugin: Version: 1.4 [Support]
  Silverlight: Version: 5.1.20125.0 - SDK 10.6 [Support]
  Flash Player: Version: 16.0.0.235 - SDK 10.6 [Support]
  QuickTime Plugin: Version: 7.7.3
  iPhotoPhotocast: Version: 7.0 - SDK 10.7
  AdobePDFViewer: Version: 11.0.07 - SDK 10.6 [Support]
  ContentUploaderPlugin: Version: 1.2 [Support]
  JavaAppletPlugin: Version: Java 7 Update 65 Check version
Audio Plug-ins: ℹ️
  TASCAM_US1xx: Version: Unknown - SDK 10.7 [Support]
  TASCAM_US122L_US144: Version: Unknown [Support]
3rd Party Preference Panes: ℹ️
  DivX  [Support]
  Flash Player  [Support]
  Flip4Mac WMV  [Support]
  Growl  [Support]
  Java  [Support]
  MacFUSE  [Support]
  Perian  [Support]
Time Machine: ℹ️
  Skip System Files: NO
  Mobile backups: OFF
  Auto backup: NO - Auto backup turned off
  Volumes being backed up:
  Macintosh HD: Disk size: 465.35 GB Disk used: 272.11 GB
  Destinations:
  Disco Time Capsule [Network]
  Total size: 497.62 GB
  Total number of backups: 19
  Oldest backup: 2013-12-17 04:01:07 +0000
  Last backup: 2014-01-09 13:10:58 +0000
  Size of backup disk: Too small
  Backup size 497.62 GB < (Disk used 272.11 GB X 3)
Top Processes by CPU: ℹ️
      17% GarageBand
      11% WindowServer
      4% coreaudiod
      2% Dock
      0% PianoPlugin
Top Processes by Memory: ℹ️
  159 MB Google Chrome Helper
  129 MB GarageBand
  116 MB Google Chrome
  82 MB Finder
  60 MB Safari
Virtual Memory Information: ℹ️
  143 MB Free RAM
  1.25 GB Active RAM
  1.15 GB Inactive RAM
  634 MB Wired RAM
  21.75 GB Page-ins
  349 MB Page-outs
Diagnostics Information: ℹ️
  Jan 8, 2015, 10:04:56 AM Self test - passed
  Jan 8, 2015, 01:44:58 AM /Users/[redacted]/Library/Logs/DiagnosticReports/fontd_2015-01-08-014458_[redac ted].crash
  Jan 8, 2015, 01:44:49 AM /Users/[redacted]/Library/Logs/DiagnosticReports/fontd_2015-01-08-014449_[redac ted].crash
  Jan 8, 2015, 01:44:04 AM /Library/Logs/DiagnosticReports/Finder_2015-01-08-014404_[redacted].crash
  Jan 8, 2015, 01:43:59 AM /Library/Logs/DiagnosticReports/Dock_2015-01-08-014359_[redacted].crash
  Jan 8, 2015, 01:43:55 AM /Library/Logs/DiagnosticReports/WindowServer_2015-01-08-014355_[redacted].crash
  Jan 8, 2015, 01:35:27 AM /Users/[redacted]/Library/Logs/DiagnosticReports/fontd_2015-01-08-013527_[redac ted].crash
  Jan 8, 2015, 01:35:17 AM /Users/[redacted]/Library/Logs/DiagnosticReports/fontd_2015-01-08-013517_[redac ted].crash
  Jan 8, 2015, 01:35:07 AM /Users/[redacted]/Library/Logs/DiagnosticReports/fontd_2015-01-08-013507_[redac ted].crash
  Jan 8, 2015, 01:35:03 AM /Users/[redacted]/Library/Logs/DiagnosticReports/fontd_2015-01-08-013503_[redac ted].crash
  Jan 8, 2015, 01:34:10 AM /Library/Logs/DiagnosticReports/WindowServer_2015-01-08-013410_[redacted].crash
  Jan 8, 2015, 01:25:14 AM /Users/[redacted]/Library/Logs/DiagnosticReports/fontd_2015-01-08-012514_[redac ted].crash
  Jan 8, 2015, 01:25:04 AM /Users/[redacted]/Library/Logs/DiagnosticReports/fontd_2015-01-08-012504_[redac ted].crash
  Jan 8, 2015, 01:24:55 AM /Users/[redacted]/Library/Logs/DiagnosticReports/fontd_2015-01-08-012455_[redac ted].crash
  Jan 8, 2015, 01:24:52 AM /Users/[redacted]/Library/Logs/DiagnosticReports/fontd_2015-01-08-012452_[redac ted].crash
  Jan 8, 2015, 01:23:51 AM /Library/Logs/DiagnosticReports/WindowServer_2015-01-08-012351_[redacted].crash
  Jan 8, 2015, 01:12:38 AM /Users/[redacted]/Library/Logs/DiagnosticReports/fontd_2015-01-08-011238_[redac ted].crash
  Jan 8, 2015, 01:12:29 AM /Users/[redacted]/Library/Logs/DiagnosticReports/fontd_2015-01-08-011229_[redac ted].crash
  Jan 8, 2015, 01:12:19 AM /Users/[redacted]/Library/Logs/DiagnosticReports/fontd_2015-01-08-011219_[redac ted].crash
  Jan 8, 2015, 01:12:16 AM /Users/[redacted]/Library/Logs/DiagnosticReports/fontd_2015-01-08-011216_[redac ted].crash
  Jan 8, 2015, 01:09:51 AM /Library/Logs/DiagnosticReports/WindowServer_2015-01-08-010951_[redacted].crash
  Jan 7, 2015, 11:43:54 PM /Users/[redacted]/Library/Logs/DiagnosticReports/quicklookd_2015-01-07-234354_[ redacted].crash