[O] org-drill extremely slow with Org 9.2.5

[Milan Zamazal]

Hi, after upgrading from Org 9.1 to 9.2, org-drill has become extremely
slow.  org-drill has never been fast, but now it stops being usable.
Everything takes much more time than before -- running `M-x org-drill',
both for the first time and again, responding to drill queries, moving
over my Org file.

My org-drill Org file has over 4,000 entries and almost 50,000 lines.
With Org 9.1, it used to be usable after running `M-x org-drill' for the
first time in the given Emacs session; after the initial Org processing,
I could move over the entries relatively smoothly.  But this no longer
helps and org-drill itself is much slower too.

Is Org 9.2 no longer capable to handle (relatively) large files with a
lot of Org properties?  Are there any tricks to speed it up?

Thanks for any advice,
Milan