Operating system: Windows-10-10.0.17134 64 Bits
Graphics card: GeForce GTX 560/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 391.35
Broken: version: 2.80 (sub 53), branch: master, commit date: 2019-03-30 19:37, hash: rB700346d377dd
Short description of error
I have scene where I put a lot boolean(and not only) modificators on one objects and when I enter into edit mode all processing erally slow (each action: movement, extrusion, etc..) And problem here in next: when you doing any action (and it took time to process it) and then press mouse button to apply action affect, but! it will not memorize position of the mouse when you pressed, and still continue doing (move to the cursor) And this really anoing because you need repeat all twice or more time. Or just seating and waiting with no mouse movement at all, when it will apply action effect.
So core problem is that: in edit mode any affect will applyes not at moment when you decide but by moment when CPU will finished calculetion of movement/action and will change your action to position where is going be mouse positioned at the moment of the end calculation... something like that.
Exact steps for others to reproduce the error
Create some worcload/heavy scene. For example by a lot subdivisions and booleans at object. When each your action will be like "under water gravity" slowed down. And then try to change(extrude/move vertext / anything) boolean part that will be used as cut area in the edit mode.