Generally, your Marlin version is quite outdated, and Marlin has significantly evolved since then.
Of course, we are Klipper fan-boys and will defend Klipper as the superior firmware, even with a knife between our teeth.
Especially with old 8-bit boards (like yours), Klipper can achieve much higher step rates and thus faster prints. However, the mechanics of your printer must be able to handle this (no software can turn a Fiat into a Ferrari).
In addition, Klipper has advanced features that can improve the quality of “lower-end” hardware at higher speeds.
For some general information, you might want to refer to:
At a quick glance, there’s nothing against running Klipper on your hardware. Of course, it has a learning curve, but it is absolutely manageable.