WebGL Performance Issues.

I have been working on/making games for WebGL for a year now, but I have always had a problem with performance. Depending on the computer and internet connection, WebGL can run very slow, or very fast. All my games work well with newer computers and higher speed internet, but not everyone has the newer computers, or the higher speed connections. So I was wondering, if any WebGL devs would have any tips on how to improve my WebGL games performance. Thanks in advance!