Use search index with Acrobat Reader on Ipad Pro

Good morning all,

I use the PDF format to distribute catalogs that will be read on Ipad Pro. The biggest catalogs are ~ 900 pages long and my problem is with the search engine on the iPad in the Acrobat reader app.

Basically, the search is very slow so from Acrobat Pro DC I incorporated a search index into my file, saved the file and transferred it to an Ipad again. Unfortunately, research is still very slow. The further away the search term is in the document, the more time it takes. This observation makes me say that the index is not used on the Ipad version.

Is this the case or is there a specific adjustment to be made?
Thank you in advance.