does charging lipo's at low amp decrease punch?

[blueb8llz]

ok cool . thats all i needed to know. cus my zippys need to be slow charged to give it time to balance all 3 cells.
what about if after everytime i use the zippys, they are all unbalanced again. Does this mean the zippys have a lost in performance? i bought these zippys used, so i have no clue how they performed when they were brand new.
my guess would be they were alot more punchy and gave more runtime as im only getting like 20 mins with a 2200mah 3s for my rc18mt.
im trying to figure out if i need a new lipo or not. ill definetly get one if im losing performance with these unbalanced packs.