Document how to optimize formulas

Discussed in https://github.com/handsontable/hyperformula/discussions/871

^{Originally posted by rackuka December 8, 2021}
I have excel workbook which I parse and provide to HyperFormula as dictionary (Record<string, string[][]>) of array of arrays. It takes 30-35 seconds for the buildFromSheets to complete loading. Profiling shows that the most of the time is consumed by buildGraph.

This time is not acceptable at all for my case where hyperformula is supposed to serve as calculation engine in server environment with the workbook be the calculation model. Latency for processing calculation request should exceed 1 second (including network latencies). So appears that loading the workbook every time is not an option (35 seconds to load).

I would appreciate for the advise as to how to improve overall time of buildFromSheets (if possible at all).

Start with discussion #871 and the reported profiling of buildFromSheets and buildGraph. Determine what optimization guidance is supported by the discussion, then document the relevant steps and expected loading behavior; the work is done when users can follow the documentation to improve or assess workbook-loading performance.