Bad performance with VSM

So, I’m not sure if this is just an issue I’ve had, but VSM seems to be very VERY finicky, and half the time causes huge performance drops. This seems very strange to me because (from my understanding) it’s supposed to be the more performant method of shadow mapping. Using the blurred version of it changes it from a chance of running bad to a guarantee of running slow. I’ve tried this on plenty of different PCs, with GPUs ranging from literally nothing to a GTX 1660 TI. The results are always the same. Anyone else having this issue? Is it only with the OpenGL renderer? I haven’t tested this with DirectX yet, but I feel the result won’t be much different.

Setting the Renderer's shadow quality to SHADOWQUALITY_BLUR_VSM indeed does drop the frame rate quite significantly.