Searchprotocolhost.exe is one of the reason to make your system slow. Following are the step(s) to stop this and make system fast.
1. Click Start -> Run or Press Windows + R
2. Type services.msc and press 'Ok' or click 'Enter'
3. Scroll down to find 'Windows Search' and double click
4. Stop the process
Another step to disable it from Startup:
5. Reapeat step number 1
6. Type 'msconfig' and press 'Ok' or click 'Enter'
7. Click on 'Startup' tab
8. Uncheck 'Windows Search' checkbox
9. Click Ok.
Restart your system.
To verify :
Open your TaskManager by pressing 'Ctrl+Alt+Del' and locate for Searchprotocolhost.exe in process tab.