In actual test, you tend to think faster. Pacing breaks concentration, try to avoid it if possible. Leave 1.5 min for any question not yet done is all you have to do.
I am a fast thinker and I get impatient easily,this is not a good thing. I become impatient about a SC in a minute or so.
To improve your RC, try to take notes. Also try to finish a reading section (8 questions each) in 10 min, with note-taking.
If you've studied OG so many times, SC doesn't take any time at all. You will be able to immediately spot the flaw in the structure of the sentence.
RC is the cornerstone of CR. If you can not do well in RC, chances are that CR will be a problem for you.