LS oil pressure slow to build

I've noticed after doing a DOD delete that my
oil pressure gauge takes about 3 seconds to
swing up to normal. I also heard the lifters
knocking this morning while the pressure was
building. After that it runs fine. When I shut
the engine off and restart the gage still
swings slow but no noise when warm.

I didn't replace the oil pump, just had to
loosen the bolts and pry it a bit to swap out
the chain tensioner.

I never noticed anything like this before. Oil
and filter are new as well.