When we launch a report in Advance Reporting or Reports and Jobs in 15.4 it appears to be slow to submit and receive the results.
I haven't seen any generic issue, however will definitely like to see what action is loading slow, you can run a browser trace and see which is taking time.
Also what is the Jaspersoft version you are using?
I agree with you. when we upgraded to 15.4, it seems to be slow as compared to earlier versions. Not sure of the reasons for this.
I have not seen any issues yet, but most of our reporting issues are around very large reports that could use some significant SQL optimization.
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