I have recently.. within the past few weeks noticed that my water pressure at all outlets has been reduced significantly. When I switch the bypass valve on the water softener I have great pressure everywhere. What is causing the lower water flow? My softener is about 6 years old.

Is there a Filter attached before / after the softener ?

No filter. Replaced the resin beads today. Waiting on a couple of O-rings then will see it that makes any difference.