Minor bug fixing and performance improvements on Drupal custom module

I have developed a private module for Drupal 7 to make a simple backoffice website for a company.
Basically, the user creates projects, work log (day, number of hours, project), spendings (day, value and project) and then I have some pages that show that information to the user in a customized way.

At this moment what I need is to fix some minor bugs:
- bootstrap table header is always fixed at the top but when scrolling, it becomes misaligned. I need the header to be always aligned or find another way to achieve the same effect with another them;
- performance issues - I think my code could be optimized (less function calls, etc).

It's very important for me to have someone that helps me solve these issues but also that explains me the process to do it so I can learn how to do it in future projects. Basically I need someone to spend 1-2h with me and together browse the code and change it to a better one and/or give some advices.