A bug introduced in 3.8.0 that was causing serious performance issues has been fixed, which will hopefully alleviate some stress from high intensity situations. The issue was causing certain particle effects to render more effects whenever they were taking a longer amount of time to render. This means that, in cases of small amounts of lag, it would progressively get worse and worse, at an exponential rate.
This resulted in plenty of issues in which a bit of lag would scale up into the game hanging for several seconds at a time. You can read the full report here, and we should hopefully see performance improving after this patch today!