I'm currently using the Freetype library to render text to my opengl es 2.0 app (both ios and android) and I've come to the point where I seriously have to consider performance. I have a store of textures (one for each character) and whenever I render text, the character calls from that texture area and then opengl binds to it, renders it to the screen... For each letter! Very inefficient. So, I'm looking into ways to make this faster, and one of the ideas I had was to pre render each word instead of each letter. So, now for the big question: How do I combine textures side by side? I know I need to create a buffer and that somehow it will come from FT_LOAD_CHAR, but I don't really know much else.
Actually, you have misunderstood how to use FreeType. You can load font using FT library and load all characters in to a single bitmap texture. Then you can just use texture coordinates to point the right UV. This link can help to some extend. Draw FreeType Font in OpenGL ES