memory usage in rsync 3.0.3 -- how much RAM should I have to transfer 13 million files?

[Aleksey Tsalolikhin]

Hi.   Let's say I have 10,000 files per directory.   If I understood
Wayne, rsync builds a list for all the files in the current dir, plus
another list for the directory being read-ahead.

So how much memory should rsync use, for 20,000 files?

I did double-check with -v, and it says "receiving incremental file
list" at the start of the rsync session.

I've also removed the -H option.

My options now are:

--numeric-ids
--perms
--owner
--group
-D
--links
--times
--block-size=2048
--recursive
-v
--ignore-times

What should I expect in terms of rsync's memory usage, please?

Best,
Aleksey