Robert, did you arrive at a satisfactory solution?
I have a similar problem: iSpring RCC7AK, 1/4" tubing, system and tank on closet floor next to fridge. Filter bypass cap in fridge. City water pressure is 60psi. The system is a few months old; I don't think any of the filters should need replacing yet.
Tank -> post filter -> remineralizer -> 4 ft of 1/4" tubing -> 1/4" push-to-connect to 1/4" compression adapter -> fridge (4 ft of 5/16")
The flow rate out of the tank is 1.2 gal/min.
The flow rate out of the remineralizer is 0.7 gal/min.
The flow rate at the fridge adapter is 0.7 gal/min.
The flow rate out of the refrigerator dispenser is 0.3 gal/min.
The fridge itself seems to be the primary offender, but before installing the RO system, the dispenser flow rate was probably close to 1 gal/min (with fridge filter installed). Any ideas on what might help increase dispenser flow would be appreciated. Raising the tank a few feet off the ground had no effect. Maybe switch everything to 3/8" tubing after the tank? Move the tank after the post filter? Cut the compression fitting off the fridge line and use a push-to-connect 1/4" - 5/16" adapter?
Thanks.