https://www.ncbi.nlm.nih.gov/pubmed/600655

http://boards.cannabis.com/threads/marijuana-and-super-duper-reaction-time.64680/

"So I have been a regular smoker since college and I am now 31. About a year ago while hanging out with a few friends one of them mentioned that she believed that because she smoked a lot of pot that she swears this has made her reaction time quicker. I immediately was surprised that she said this, It had confirmed what I thought was true about myself for many years. I had been noticing that over the years my eye hand reaction time was phenomenal and wondered if my smoking had anything to do with it. Others had seen some of my reflexes and commented on it as well. I still do things that amaze me after I actually realize what happened. Me and this friend talked about it quite a bit and she also stated that she noticed a huge decline in her reaction time when she stopped smoking for 6 months because of some stupid boy she was dating. After resuming smoking her reaction time increased."

https://www.businessinsider.com.au/how-marijuana-affects-working-out-2015-1