Revise SolutionStep and fix performance problems

[michakraus]

No description provided.

[codecov]

Codecov Report

❌ Patch coverage is 83.92857% with 18 lines in your changes missing coverage. Please review.
✅ Project coverage is 80.64%. Comparing base (dcefa83) to head (0109f34).
⚠️ Report is 6 commits behind head on main.

Files with missing lines	Patch %	Lines
src/solutionstep.jl	85.88%	12 Missing ⚠️
src/extrapolation/midpoint.jl	60.00%	4 Missing ⚠️
src/integrate.jl	83.33%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #15      +/-   ##
==========================================
- Coverage   81.50%   80.64%   -0.87%     
==========================================
  Files          17       17              
  Lines         611      589      -22     
==========================================
- Hits          498      475      -23     
- Misses        113      114       +1     

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