Rudolf Adamkovič <rudolf@adamkovic.org> writes:

> [...], and indeed, and the code above resulted in 1098 allocations of
> 4.72 MB, totaling ~5.18 GB, and they are all like these: [...]

Okay, I could not let go before sleep and investigated further.  See the
attached patch.  With it, the never-freed 5.18 GB of RAM is fixed for:

(dotimes (x 1000)
  (let ((frame (make-frame-command)))
    (sleep-for 0.01)
    (delete-frame frame)))

P.S. The remaining 5.22 - 5.13 ~= 100 MB is wasted due to bugs elsewhere.

Rudy