Illustrator lagging, for no apparent reason

[sk81]

I have a Macbook Pro that's only a year old and Illustrator is lagging by about 1-2 seconds each time I delete an anchor point, use the pen tool, move the object, etc.

Things I've tried:

• making my illustration smaller since it has a lot of points, didn't help. It's all vector on an 8.5in x 11in size artboard (300 dpi).  So not gigantic
• Restarting

I've checked the Activity Monitor and Illustrator takes up roughly 50% CPU when I'm using it. And everything else that's running is below 6%. (There's nothing running harder than Illustrator)

Thanks in advance! This is driving me nuts!! 

[sk81]

Also I should have mentioned that I'm using a bluetooth mouse and keyboard. The lag happens with both a keyboard click (such as the delete key) and mouse actions equally. Doesn't seem to be related to those since those 2 bluetooth items work just fine in other programs. 

[sk81]

Ok for some unknown reason - right after I posted this question, Illustrator stopped lagging!! I thought surely the problem would start back up but it's been 24 hrs and it hasn't happened again. Fingers crossed.