Third-party system modifications are a common cause of instability and poor performance. The following procedure will help identify which such modifications you've installed. Don’t be alarmed by the complexity of these instructions -- they’re easy to carry out and won’t change anything on your Mac.
Reboot as usual (not in safe mode) if you haven't already done so. Launch the Terminal application, copy or drag -- do not type -- the line of text below into the window, and press return:
kextstat -kl | awk ' !/apple/ { print $6 $7 } '
Post the lines of output (if any) that appear below what you just entered (the text, please, not a screenshot.)
Next, do the same thing with this line:
sudo launchctl list | sed 1d | awk ' !/0x|apple|com\.vix|edu\.|org\./ { print $3 } '
That's one line, not two. You'll be prompted for your login password, which won't be displayed when you type it. You may get a one-time warning not to screw up. You don't need to post the warning.
Next, this command:
launchctl list | sed 1d | awk ' !/0x|apple|edu\.|org\./ { print $3 } '
Again, one line. Finally, one more:
ls -1A {,/}Library/{Ad,Compon,Ex,Fram,In,La,Mail/B,P*P,Priv,Qu,Scripti,Se,Sta}* 2> /dev/null
Remember, this is all drag-and-drop or copy-and-paste, whichever you prefer -- no typing, except your password.
You can then quit Terminal.