I get almost all of my content from TSR, and only from featured artists, so I don't have many issues with the quality of the work. Most of the clothing and hairstyles I get are very good and I think they look quite good on my sims. Maybe that's just me, though. Some people might argue that it looks out of place, but I personally don't think so.
I'm not a huge fan of many of the alpha skintones, either. I was when I FIRST got the game, but now I usually don't even use a skintone at all. Sometimes my sims look better with it and sometimes they don't. Some alpha makeup gets me a little on edge too.. like lipsticks. I have a few downloaded that look weird and when I find the time I'll probably search for and delete them.
As for lag, I don't really get any. I recently got a new computer and it doesn't run sims 3 as well as my old one so I really only play ts3 when I have a lot of time on my hands as loading is a pain. Sims 4 is really quick and easy to boot up which works well with a college schedule. The load times have increased from when I first started playing again, but I had no expansion or game packs except for get to work back then, so it's only natural that loading time increased.
Despite the fact that I said I detest maxis match, I did download some for males since male custom content is hard to come by. I don't really put too much work into my male sims either for that reason. I also sometimes use maxis match on the parents of sims in my storytelling games. There are some cute mm hairs that I wish came in alpha, but I just don't think I could have my main character have mm. I just don't like the way it makes my sims look.