Using "reason for" without using "having" after "for"

I have this phrase:

Another reason for having poor performance earlier but better performance in later sessions...

I just wonder if there is a way to get rid of "having" or is it necessary? How about something like this:

Another reason for the poor performance initially and better performances in subsequent sessions...

I feel like in this case initially does not fit well. Any suggestions for building this sentence correctly and concisely?

The main thing that’s right with those examples is (another) reason for…

… poor performance earlier but better performance in later sessions… is more of a problem than a context.

… the poor performance initially and better performances in subsequent sessions… is less of a problem and still, more a problem than a context.

having makes little relevant difference but if you could correct the rest then it prolly would be better to drop having.

Another reason for performing poorly at first [...]

Most sentences of a similar format to the original can be reworked like this. I won't say it's better or worse style, merely a different option.

You can change "initially" from an adverb to an adjective: "poor initial performance". Another option is to make "performance" the subject: "Another reason for performance being poor at the beginning and better later on ..."