Thank you SASKiwi for your prompt reply.
My main table has to contain about 22 000 000 of rows of data with about 20 columns.
Every hour, there will be removed ~1000 of rows and appended another ~1000 rows,
what makes it less than 1 %.
I did not try any loading tests and honestly I can't think of any for now.
I did try to do deleting with IMSTAT, but for some reason, deleting ~90000 rows from table with 200 000 rows took me more than 10 minutes...