i used to do stims and weed before every workout. for many years. i find that it distorts my perception of time, fucking up my rest between sets and total workout duration, and it also makes it tough to have consistant effort. one day 100 lbs might be enough, the next ill feel like i need 150. etc.
i dont like working out on any sort of drugs , not caffiene, weed, or anything these days. i find im able to take my time, focus on the workout and not the high, and i can more accurately monitor progress because there arent wild fluctuations in my strength, endurance, etc.