In my own experience, booting Fedora after installing on the same drive of the same computer that previously held Windows or even Ubuntu, Fedora boots faster and then launches Firefox faster. So you are implying an uncommon problem.
I once installed Fedora (regular install, not “live”) on the cheapest 16GB USB device I could find at Walmart. THAT booted horribly slow and launched firefox slowly. Basically unusable, lesson learned. Some USB sticks are too slow for use as an OS and a regular install on slow media can be slower than a “live” ISO on the same media (assuming a fast computer with a lot of ram).
I always turn off the supposedly-user-friendly feature of hiding all the messages during boot up. So if something does stall, I immediately know what I need to fix. I recommend you do the same. If Fedora is slower than some other OS was on the same hardware and you installed Fedora on reasonable media, then some real diagnosis is called for and those messages are part of it. But if you prefer, you can look at the time stamped log after boot up is done. If you don’t want to look during boot up (which can be a bit intimidating) you don’t need to.