I have an Ancestry tree with over 4000 people and I downloaded it and uploaded the GEDCOM to WikiTree in June 2020. I still haven't finished adding the profiles to WikiTree! It takes a lot of determination. Here are a few pointers:
If your GEDCOM has 4000 people in it then you may have more than 10,000 suggestions of possible matches and you will have to match or reject each one.
You say you have a larger tree - make sure you don't create a GEDCOM with more than 5000 people. That is the max that WikiTree allows for a GEDCOM upload.
The profiles created in WikiTree by GEDCOMpare are ugly and not conforming to the current recommendations on how to format profiles. Because of this I ended up writing a browser extension to reformat them ( WikiTree AGC ).
Having added a lot of profiles I now wonder if it would have been better to create them manually. I think the WikiBEE extension or the WikiTree X extension can help speed up the adding of profiles from Ancestry profiles. Then you can use the WikiTree Sourcer extension to take the sources from Ancestry and add them to the WikiTree profile (with narrative text). One advantage to doing it this way is that, if you are still adding to your Ancestry tree, you are always working from the latest version of it - rather one that you exported a year ago. It is a tough call whether to use the GEDCOM route. It is a bit faster (after you go through all the suggestions) but you end up with better source citations the other way.