If a document uses a lot of SEARCH and VLOOKUP functions, then enabling regular expressions globally in a Calc document leads to an extreme performance hit.
Most of the time it turns out that only the SEARCH function needs RegEx support to get a value, while the VLOOKUPs just search for that found value.

Providing a REGEXSEARCH function, as done by Google Docs' REGEXEXTRACT [1], would help to keep the performance hit low, as RegEx would only be used when necessary. THis would also avoid additional escaping in VLOOKUPs.

Thanks for reading
Maddes

[1] https://support.google.com/docs/answer/3098244