What are the best programming practices to improve performance?

What are the best programming practices to improve performance?

Hello,
 
I find that Zoho is a bit slow when opening a stateless form for editing and I'm wondering if there are some best programing practices to enhance performance.
 
For example I've realised that:
 
1) Loading data for a dropdown box that depends on other dropdown box that has to be also loaded deteriorate loading performance.
 
2) If the menu has many views or forms also deteriorate perfomance as the many has to be loaded also when opening the stateless form.
 
But, I would like to know if there are other best practices to apply. For example:
a) I was wondering if using functions could enhance performance, in case Zoho download functions through a javascript file that could be cached. I don't know if Zoho works in that way.
b) I don't know if Zoho caches Forms source code in the browser temporary files until there were a new version or not.
 
I would like to understand where Zoho takes more time when loading a Stateless Form for editing a register. This knowledge I think could help me when programming.
 
Thanks for any advice you could provide me.
 
Fidel