Out of curiosity, was this a web text editor? It's difficult to imagine that you'd be able to be ahead of real native text editors with a solo project.
Text rendering is extremely hard, but there already exist optimized libraries with hardware acceleration. Web browsers in particular have very optimized text rendering engines. It's still slow, but it's faster then for example terminal based text rendering. The bottleneck in text rendering is not rendering per see, but actually putting the pixels onto the screen. Browsers have a disadvantage compared to native because of complex rendering pipeline, while native have more low level access. I for example tried to make a bitmap text renderer to see if it could be made any faster, but it was much slower then existing rendering API's - that's how optimized they are. Yet they are still slow. Rendering a full screen of text takes around one millisecond.
That's however well into the 60 times per second refresh time budget, which lets you spend the rest of the time budget doing stupid things like parsing the whole document on every key stroke.
