I noticed that I am only now getting severe lag with asteroid belt systems, compared to 1.13. In 1.13, I was able to look at any system without any noticeable lag, whereas now asteroid systems take me down to 3 fps or so. Nebulas also slow me down now, whereas they did not in 1.13, but not as much as asteroid belts.
If it's an Nvidia card, it's possibly the render frames ahead function. Apply coolbits to unlock all control panel features, then go into advanced 3D settings. There should be a "Max frames to render ahead feature" that has a 3. Reducing that might help.
This is also my greatest complaint on the UI side, and happens all the time (no SLI though, just a humble Geforce2Go getting 3-10 frames/sec). Cursor movement shouldn't be reliant on frame rate though.