New Org (from main) and slow clocking

[Marcin Borkowski]

Hi all,

I have just updated my Org (from the main branch, Org mode version
9.6.1, release_9.6.1-253-g74eb0f), and I noticed an issue with clocking.
I have an "ongoing" task which already accumulated 7000+ clock entries,
and clocking in takes close to 90 seconds.  It was instantaneous before
(version 9.6-pre, release_9.5.5-853-g7b9d8e).  What can I do now?

And how can I downgrade?  (I tried the "logical" thing, i.e., I checked
out a "tmp" branch at tag release_9.6.1 and ran "make update", but it
didn't work because it (obviously) couldn't pull the "tmp" branch.

Alternatively, since Org mode is much more mature now than a few years
ago, how can I get rid of my Git-based installation in favor of the Elpa
package (which, I assume, should be much more stable/bug-free)?  (I
understand that by using bleeding edge Org mode I risk a bit, and maybe
it's time to trade new/shiny for safe...)

TIA,

-- 
Marcin Borkowski
http://mbork.pl