Early 2011 MacBook Pro incredibly slow after installing Mavericks

Question

I'm really hoping someone can help me out. As per the subject line, I installed Mavericks on day one (and learned my lesson!).
Since installing Mavericks my MacBook Pro runs incredibly slow. If I open the Mail App and Safari - it almost grinds to a halt. I have the "Memory Clean" App which I now have to run constantly (it appears to help a little) and I try to only launch one app at a time where possible, but it's not really pratical.
As an aside, my MacBook ran really well with Mountain Lion, so there's little doubt to my mind that Mavericks is the culprit.
I'd be eternally grateful for any help & advice :-)
I spotted other people advise running EtreCheck, here are my results:
Hardware Information:
          MacBook Pro (13-inch, Early 2011)
          MacBook Pro - model: MacBookPro8,1
          1 2.3 GHz Intel Core i5 CPU: 2 cores
          4 GB RAM
Video Information:
          Intel HD Graphics 3000 - VRAM: 384 MB
System Software:
          OS X 10.9.1 (13B42) - Uptime: 0 days 0:13:54
Disk Information:
          Hitachi HTS545032B9A302 disk0 : (320.07 GB)
                    EFI (disk0s1) <not mounted>: 209.7 MB
                    Macintosh HD (disk0s2) /: 319.21 GB (33.32 GB free)
                    Recovery HD (disk0s3) <not mounted>: 650 MB
          MATSHITADVD-R   UJ-8A8 
USB Information:
          Apple Inc. FaceTime HD Camera (Built-in)
          Apple Inc. Apple Internal Keyboard / Trackpad
          Apple Inc. BRCM2070 Hub
                    Apple Inc. Bluetooth USB Host Controller
          Apple Computer, Inc. IR Receiver
FireWire Information:
Thunderbolt Information:
          Apple Inc. thunderbolt_bus
Kernel Extensions:
          com.globaldelight.driver.BoomDevice          (1.1 - SDK 10.9)
          net.telestream.driver.TelestreamAudio          (1.1.0 - SDK 10.8)
Startup Items:
          Jaksta: Path: /Library/StartupItems/Jaksta
Problem System Launch Daemons:
          [failed] com.apple.wdhelper.plist 3rd-Party support link
Problem System Launch Agents:
Launch Daemons:
          [loaded] com.adobe.fpsaud.plist 3rd-Party support link
          [loaded] com.bourgeoisbits.cloak.cloakd.plist 3rd-Party support link
          [loaded] com.bourgeoisbits.cloak.cloakproxyd.plist 3rd-Party support link
          [loaded] com.google.keystone.daemon.plist 3rd-Party support link
          [loaded] com.macpaw.CleanMyMac2.Agent.plist 3rd-Party support link
Launch Agents:
          [loaded] com.amazon.sendtokindle.launcher.plist 3rd-Party support link
          [loaded] com.google.keystone.agent.plist 3rd-Party support link
User Launch Agents:
          [loaded] com.macpaw.CleanMyMac2Helper.diskSpaceWatcher.plist 3rd-Party support link
          [loaded] com.macpaw.CleanMyMac2Helper.scheduledScan.plist 3rd-Party support link
          [loaded] com.macpaw.CleanMyMac2Helper.trashWatcher.plist 3rd-Party support link
User Login Items:
          Boom
          PopClip
          Caffeine
          Fantastical
          AppTrap
          Dropbox
          Alfred 2
          Cloak
          ScreenFlowHelper
          Google Chrome
Internet Plug-ins:
          o1dbrowserplugin: Version: 3.18.3.12840 3rd-Party support link
          SpeedDownload Browser Plugin: Version: 2.1.5 - SDK 10.6 3rd-Party support link
          Default Browser: Version: 537 - SDK 10.9
          Flip4Mac WMV Plugin: Version: 2.4.1.4 3rd-Party support link
          AmazonMP3DownloaderPlugin101750: Version: AmazonMP3DownloaderPlugin 1.0.17 - SDK 10.4 3rd-Party support link
          Silverlight: Version: 5.1.10411.0 - SDK 10.6 3rd-Party support link
          FlashPlayer-10.6: Version: 11.9.900.170 - SDK 10.6 3rd-Party support link
          Flash Player: Version: 11.9.900.170 - SDK 10.6 3rd-Party support link
          QuickTime Plugin: Version: 7.7.3
          googletalkbrowserplugin: Version: 3.18.3.12840 3rd-Party support link
          npgtpo3dautoplugin: Version: 0.1.44.28 - SDK 10.5 3rd-Party support link
          iPhotoPhotocast: Version: 7.0 - SDK 10.8
          JavaAppletPlugin: Version: 14.8.0 - SDK 10.9 Outdated! Update
Audio Plug-ins:
          BluetoothAudioPlugIn: Version: 1.0 - SDK 10.9
          AirPlay: Version: 1.9 - SDK 10.9
          AppleAVBAudio: Version: 2.0.0 - SDK 10.9
          iSightAudio: Version: 7.7.3 - SDK 10.9
User Internet Plug-ins:
          CitrixOnlineWebDeploymentPlugin: Version: 1.0.105 3rd-Party support link
          EMusic: Version: EMusic 1.0.0 3rd-Party support link
3rd Party Preference Panes:
          AppTrap  3rd-Party support link
          Flash Player  3rd-Party support link
          Flip4Mac WMV  3rd-Party support link
          Hazel  3rd-Party support link
          Perian  3rd-Party support link
Bad Fonts:
          None
Old Applications:
          /Applications/iWork '09
          SLLauncher:          Version: 1.0 - SDK 10.5 3rd-Party support link
                    /Library/Application Support/Microsoft/Silverlight/OutOfBrowser/SLLauncher.app
          Attachment Tamer Helper:          Version: 3.1.2 - SDK 10.5 3rd-Party support link
                    /Users/derricksutton/Library/Mail/Bundles (Disabled)/Attachment Tamer.mailbundle/Contents/Resources/Attachment Tamer Helper.app
          Nisus Thesaurus:          Version: 1.1 - SDK 10.4 3rd-Party support link
          Amazon MP3 Downloader:          Version: INFO_PLIST_VERSION - SDK 10.4 3rd-Party support link
Time Machine:
          Skip System Files: NO
          Mobile backups: ON
          Auto backup: YES
          Volumes being backed up:
                    Macintosh HD: Disk size: 297.29 GB Disk used: 266.26 GB
          Destinations:
                    Seagate Expansion Drive [Local] (Last used)
                    Total size: 465.44 GB
                    Total number of backups: 10
                    Oldest backup: 2013-09-21 16:05:10 +0000
                    Last backup: 2013-12-31 20:05:10 +0000
                    Size of backup disk: Too small
                              Backup size 465.44 GB < (Disk used 266.26 GB X 3)
          Time Machine details may not be accurate.
          All volumes being backed up may not be listed.
Top Processes by CPU:
              28%          WindowServer
               5%          Google Chrome
               2%          Dock
               1%          Fantastical
               1%          hidd
Top Processes by Memory:
          135 MB          Google Chrome Helper
          98 MB          mds_stores
          90 MB          Finder
          86 MB          Google Chrome
          61 MB          EtreCheck
Virtual Memory Information:
          612 MB          Free RAM
          1.47 GB          Active RAM
          601 MB          Inactive RAM
          1.04 GB          Wired RAM
          523 MB          Page-ins
          2 MB          Page-outs

Answer 1

CleanMyMac is probably your problem.
CleanMyMac is crapware.
Crapware is anything that purports to "optimize",  "clean", "accelerate", "monitor", or "protect" your Mac. These apps are unnecessary, poorly written, overpriced (if they were free, they'd still be overpriced), and harmful. The people who sell this stuff know this, but they keep selling it because people keep buying it. They can damage your OS and be difficult to uninstall.
I would try to uninstall it, but if that fails, you may have to erase your HD and do a clean install.