DOC/WIP: performance tips for large displays

[ZLLentz]

I think completing this would be useful.

During the EPICS codeathon (may 2022) we identified some performance scaling issues with large displays- I'd like to investigate further what kinds of tips or tools we can include to help these displays perform better.

[codecov-commenter]

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Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 61.97%. Comparing base (25ad437) to head (4e3f4c7).
⚠️ Report is 1383 commits behind head on master.
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Additional details and impacted files

@@            Coverage Diff             @@
##           master     #862      +/-   ##
==========================================
- Coverage   61.97%   61.97%   -0.01%     
==========================================
  Files          98       98              
  Lines       12008    12005       -3     
==========================================
- Hits         7442     7440       -2     
+ Misses       4566     4565       -1     

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[ZLLentz]

Some other ideas of performance tips to include:

• fast-running slots
• using signals as callbacks
• Qt.QueuedConnection
• How to set up custom PyDMChannel instances

[ZLLentz]

Another idea:

• How to use profiler outputs