If the filter is full, then you're basically in a kinetic situation with oil flow. Much depends on now fast the static mass of the "oil column" can accelerate to whatever the pump is delivering in output. If all things are "normal" the media should have "fractionally marginal" (is that redundant?) impact on anything. If the pump has no trouble pumping it's full output to the engine without going into relief (important- often ignored factoid) ..then you're getting 100% flow to the engine. Can't happen any other way. If, OTOH, you've got heavy static mass that cannot accelerate to the pump output level, then the pump will be in relief ..and you may reach the bypass valve threshold in pressure differential. If you have larger empty oil passages, then you can see a delay to (peak) pressure. This delay is the difference in between the time to pressure at 100% pump output and the time to pressure at the that flow rate reduced by the percentage that the bypass valve represents in MAX opening threshold. That is, 100 psi @ 1 gpm. 15psid bypass ...min flow rate at startup (it's a curve ..so be forgiving in critique) ..85% flow minimum (naturally, if your peak is 50psi with the same 15psid bypass- then the % is lower). THIS statement is ONLY referring to what the filter can alter. Naturally, if you've got a super heavy mass of oil, it too will represent higher developed back pressure between the pump and the filter to the point of relief as it views it (just getting it there or attempting to move it). This will cause additional "tire spinning" before the pump stops doing its burn out and connects the flow applied with the flow in motion.