What is the Shar'i ruling regarding a congregant following an Imam who is extremely fast in his prayer, preceding him in the pillars or beginning a pillar before the congregant completes his pillar? And is it permissible for the congregant to hasten his remembrance or move to the next pillar before completing the obligatory remembrance to keep pace with the Imam, or before completing the recitation of Al-Fatiha if the Imam bows?

If the Imam stands up for the third rak'ah while you are reciting the tashahhud, complete all its words while sitting, then stand up. The first tashahhud is obligatory according to the Hanbalis, and to avoid their differing opinion, it should be completed entirely while sitting, because completing it is obligatory. However, if the Imam bows before you complete the Fatihah, finish reading it, then catch up with him; your delay is excused. It is advisable to quicken your recitation if the Imam tends to bow early, as following him and avoiding scholarly differences is more preferable.