I have struggled, literally for years, with Quicken being dog slow to start. It could take 30+ seconds to start. From what I could remember, this problem has existed since I first installed Windows 10.
The title gives the answer away, but yes, it’s exactly what it says – some applications on Windows will load every single font on the system before loading the rest of the application. If you have a lot of fonts – say, because you’re a designer or illustrator or whatever – you’re going to feel this.