As DNN is fully Community driven now, you can suggest improvements on github.
Make sure you focus on the technical aspect of what you would like to be changed to the code base, not just log that there's an issue.
If any of the volunteers decides to spend time on working on the issues you logged, the fix could get incorporated in a future version of DNN. But there is no guarantee. As an alternative you can obviously do a pull request yourself, or even pay someone to do this for you if the change is important to you. But in that case, it's always wise to first discuss the change with the issue you created, to improve the chance that the fix will be accepted.

Good catch. Now, the question is: how can we move forward? Because as Timo stated: this is not a forum where you can post requests and expect them to be granted. In order to get someone improve the code, there are a couple of ways to do so:

1. you create a pull request on github (https://github.com/dnnsof...nn.Platform/issues). Someone will review the code and if all is well, it will be merged into a next version.
2. you get someone else to create a pull request for you. Now, there are 2 ways to move forward:
   1. As you can see, for the most recent version (https://github.com/dnnsof...n.Platform/releases) a tremendous amount of work has been done by a great group of volunteers. They all put in a lot of hours, free of charge, to make the platform a better product. If you detect an issue that impacts a lot of the community members, it is more likely that someone will pick it up.
   2. If you want more certainty that this gets priority, you can hire someone to do the work. Recently, I worked together with a developer to create a GTM connector which will now become part of the DNN core. 

In both cases, it would be very helpful if you can elaborate more on what the problem is and what the desired solution is. Because I don't think many of us understand what 'first content paint' is. I would really appreciate if you took the time and effort to get this on the road.  

One more note: your vanilla DNN install (demostore) can not be reached so I can not verify that. But if you look at gosmartlist the cause has nothing to do with DNN. A better tool for insight is in this case the Google page speed. Almost all (about 30-40) issues are related to the DNNGo skin. You went full force to include all of the css, javascript, bootstrap etc etc.  

Hope this helps and certainly hope to see your analysis on this topic.