SSRS running Slow all the time

I don't have an issue navigating through the reports, however when running the reports it takes longer time for the results to come up on a secondary system than the prod system.
the secondary system has double the amount of RAM of the prod system and all that's running on it is replication of the database i'm running the reports against. I tweaked IIS as best as i could but still issue stands.

any help is much appreciated.