Bex queries run slower after SP 18 upgrade

We upgraded to 7.5 SP18 and since then our queries have been running much slower. When analyzing in RSRT, it shows that returning the result (query display) in list mode runs fast but any other mode (ABAP, JAVA) makes it very slow. Running a trace on a test query shows a lot of select statements being run even though the query is extremely basic. It only has 1 KF as output. It looks like it's going thru all the CKFs and RKFs on the Multiprovider even though they are not being used.

Any thoughts on this problem? Has anyone faced a similar issue? Thanks!