What maintenance can I perform on my GROHE 33 755 KD0 Ladylux Cafe Pull-Out kitchen faucet?
Try removing, disassembling (take notes!), and soaking the faucet head in a mix of hot water and vinegar (50/50) for a short while (e.g. an hour or two), to help remove any tap water mineral deposits that may have made their way into the head of your faucet and that are restricting your water flow.

Faucet heads typically have very fine passages and/or aerator mesh, and it's not uncommon for a build-up of tap water mineral deposits to cause water flow problem over time.  I've experienced this first hand, and a good vinegar soak did the trick.

Best of luck.