[cflsystems]

Well it is somewhere in between. XC is build with the goal that you can just install it and it will work for any type of site and any type of business. While this gives it broader audience at the same time it is its weakest feature. It has to satisfy way too many requirements for all kinds of usage.

Because of that XC codebase is huge and bloated. The worst portion of it is the css. XC devs still don't know how to properly use css and build a theme around it. Then you have the option to position elements with annotation clause from either template or class and thsi in many cases may break the css. Then you are forced to apply even more css to fix that...
It's an endless battle going back and forth given the fact that you also have 3rd party modules trying to get in between.
But it's not only that. You have XC devs including "cool" stuff and new features without the actual need for them. This contributes to more bloated code and slower load times.
The final product has way too much javascript code in it and heavily relies on it. Even simple things were js is not needed are build based on on js code.
I know what you are saying as I deal with this every day. But the only way to address these issues is to integrate a theme from scratch. Basically having custom module that dumps all stock css, js where possible, and redo all of the css. Then you will need to also address 3rd party modules and how they hook up to the system with their own resources.



It's not an easy tasks and you can imagine the time that will take doing all of this too.
So basically you are stuck with whatever XC has to offer out of the box, then modify it to fit your needs/vision as best as possible. Make sure everything that you do not use is removed or off. XC comes with tons of modules preinstalled and enabled and 2/3 of them are not needed for any store - remove them. Anything core-based that is not needed - you can turn it off with custom module. The goal is to have as less code as possible to run for every request.


There are lots of sql queries running with every page load - this can be optimized as well.
Proper server optimization and resources too are important.
Use of CDN, use of cache.



There are lots of ways however I have not seen an XC5 store yet to load pages for less than 3+ sec
Actually one store, client of mine, loads any page anywhere between 0.5 and 1.5 sec. Server is nginx and the site is very clean, stripped down to the absolute minimum needed.
The more you add, the more modules and fancy stuff the worst is going to get.


However XC5 is good and getting better. But good luck with having a nice properly coded theme any time soon.