Looks like you may have duplicate jobs. The code you posted that runs 1pm does all that the integrity check and optimisations do. You may be able to disable one of those jobs.

That step's also doing a lot of unnecessary stuff. For each table in the DB, it's doing an index rebuild, followed by an index defrag, followed by a statistics update.

Reindex does all that a defrag and a stats update does, and more. You should remove the IndexDefrag and Update Statistics from than.

(Or perhaps disable that job totally)

And you definitly want to take these two lines out.

That's telling SQL to empty the procedre cache and clear all the data buffers. For a while after that the system will run slower as procedures have to be recompiled and data has to be fetched from disk rather than memory.