Yosemite installation made my MacBook very slow. Need some help

Question

Hi all. I read different threads in his direction but didn't find solution for me. I hope that here somebody could help me. Below I paste results from Etrecheck:
EtreCheck version: 2.1.8 (121)
Report generated February 13, 2015 at 9:40:56 PM GMT+2
Download EtreCheck from http://etresoft.com/etrecheck
Click the [Click for support] links for help with non-Apple products.
Click the [Click for details] links for more information about that line.
Hardware Information: ℹ️
    MacBook Pro (13-inch, Late 2011) (Technical Specifications)
    MacBook Pro - model: MacBookPro8,1
    1 2.4 GHz Intel Core i5 CPU: 2-core
    8 GB RAM Upgradeable
        BANK 0/DIMM0
            4 GB DDR3 1600 MHz ok
        BANK 1/DIMM0
            4 GB DDR3 1600 MHz ok
    Bluetooth: Old - Handoff/Airdrop2 not supported
    Wireless:  en1: 802.11 a/b/g/n
    Battery Health: Normal - Cycle count 127
Video Information: ℹ️
    Intel HD Graphics 3000 - VRAM: 512 MB
        Color LCD 1280 x 800
System Software: ℹ️
    OS X 10.10.1 (14B25) - Time since boot: 1:37:46
Disk Information: ℹ️
    Samsung SSD 840 Series disk0 : (250.06 GB)
        EFI (disk0s1) <not mounted> : 210 MB
        Recovery HD (disk0s3) <not mounted>  [Recovery]: 650 MB
        Macintosh (disk1) / : 248.83 GB (234.16 GB free)
            Core Storage: disk0s2 249.20 GB Online
    MATSHITADVD-R   UJ-8A8 
USB Information: ℹ️
    Apple Inc. Apple Internal Keyboard / Trackpad
    Apple Inc. BRCM2070 Hub
        Apple Inc. Bluetooth USB Host Controller
    Apple Inc. FaceTime HD Camera (Built-in)
    Apple Computer, Inc. IR Receiver
Thunderbolt Information: ℹ️
    Apple Inc. thunderbolt_bus
Gatekeeper: ℹ️
    Mac App Store and identified developers
User Login Items: ℹ️
    None
Internet Plug-ins: ℹ️
    Default Browser: Version: 600 - SDK 10.10
    QuickTime Plugin: Version: 7.7.3
3rd Party Preference Panes: ℹ️
    None
Time Machine: ℹ️
    Time Machine not configured!
Top Processes by CPU: ℹ️
         5%    WindowServer
         3%    storedownloadd
         1%    Activity Monitor
         1%    sysmond
         1%    ps
Top Processes by Memory: ℹ️
    301 MB    loginwindow
    77 MB    WindowServer
    69 MB    sandboxd
    69 MB    com.apple.WebKit.WebContent
    60 MB    Finder
Virtual Memory Information: ℹ️
    4.64 GB    Free RAM
    1.69 GB    Active RAM
    1.01 GB    Inactive RAM
    1.25 GB    Wired RAM
    1.57 GB    Page-ins
    0 B    Page-outs
Diagnostics Information: ℹ️
    Feb 13, 2015, 09:25:17 PM    /Users/[redacted]/Library/Logs/DiagnosticReports/Finder_2015-02-13-212517_[reda cted].crash
    Feb 13, 2015, 07:53:07 PM    Self test - passed

Answer 1

Whatever your problem is, there is nothing here to support being slow.
Try these in order testing your system after each to see if it's back to normal:
1. a. Resetting your Mac's PRAM and NVRAM
    b. Intel-based Macs: Resetting the System Management Controller (SMC)
2. Restart the computer in Safe Mode, then restart again, normally. If this doesn't help, then:
Boot to the Recovery HD: Restart the computer and after the chime press and hold down the COMMAND and R keys until the Utilities menu screen appears. Alternatively, restart the computer and after the chime press and hold down the OPTION key until the boot manager screen appears. Select the Recovery HD and click on the downward pointing arrow button.
3. Repair the Hard Drive and Permissions: Upon startup select Disk Utility from the Utilities menu. Repair the Hard Drive and Permissions as follows.
When the recovery menu appears select Disk Utility. After DU loads select your hard drive entry (mfgr.'s ID and drive size) from the the left side list.  In the DU status area you will see an entry for the S.M.A.R.T. status of the hard drive.  If it does not say "Verified" then the hard drive is failing or failed. (SMART status is not reported on external Firewire or USB drives.) If the drive is "Verified" then select your OS X volume from the list on the left (sub-entry below the drive entry,) click on the First Aid tab, then click on the Repair Disk button. If DU reports any errors that have been fixed, then re-run Repair Disk until no errors are reported. If no errors are reported click on the Repair Permissions button. Wait until the operation completes, then quit DU and return to the main menu. Select Restart from the Apple menu.
4. Reinstall Yosemite: Reboot from the Recovery HD. Select Reinstall OS X from the Utilities menu, and click on the Continue button.
Note: You will need an active Internet connection. I suggest using Ethernet if possible
            because it is three times faster than wireless.
5. Reinstall Yosemite from Scratch:
Be sure you backup your files to an external drive or second internal drive because the following procedure will remove everything from the hard drive.
How to Clean Install OS X Yosemite
Note: You will need an active Internet connection. I suggest using Ethernet if possible
            because it is three times faster than wireless.