Core: Improves performance of `orm_cached` with an in-memory cache

[Daverball]

Commit message

Core: Improves performance of orm_cached with an in-memory cache

TYPE: Performance

Checklist

• [ ] I have performed a self-review of my code
• [ ] I have tested my code thoroughly by hand
• [ ] I have added tests for my changes

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 86.79245% with 7 lines in your changes missing coverage. Please review.

Project coverage is 86.62%. Comparing base (cc4d60f) to head (b091740). Report is 701 commits behind head on master.

Files with missing lines	Patch %	Lines
src/onegov/core/orm/cache.py	89.47%	4 Missing :warning:
src/onegov/core/orm/utils.py	76.92%	3 Missing :warning:

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1029      +/-   ##
==========================================
- Coverage   86.74%   86.62%   -0.12%     
==========================================
  Files        1171     1171              
  Lines       78416    78450      +34     
==========================================
- Hits        68019    67959      -60     
- Misses      10397    10491      +94     

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[Daverball]

Continued in #1524