System Information
Operating system: Windows-10-10.0.17763 64 Bits
Graphics card: GeForce GTX 1080 Ti/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 430.64

Blender Version
Broken: version: 2.80 (sub 74), branch: master, commit date: 2019-07-08 23:33, hash: rBac8c795429f9
Worked: (optional)

Short description of error
When empty mesh cache modifier without any mesh cache is applied onto a high poly mesh (Around 400k triangles) the playback and timeline scrubbing performance is significantly affected despite no file even being loaded yet. On top of that, performance is not recovered even when modifier display is disabled.

Exact steps for others to reproduce the error

1. In an empty new blender file, subdivide the default cube a few times so it has over 400k triangles
2. In the modifier list, apply the Mesh Cache modifier
3. Notice the slow animation playback and laggy timeline scrubbing
4. Disable the viewport display of the Mesh Cache modifier by clicking the display icon in modifier list
5. Notice the performace loss still persists

Result: Mesh Cache modifier slows down playback performance even without any file loaded, and disabling the modifier display does not help to recover performance
Expected: Mesh Cache modifier does not affect playback performance until mesh cache is loaded and displayed. When Mesh Cache modifier display is disabled, the modifier no longer impacts performance.