Hi JaniN,
I've double checked just before reply to you. The problem did get fixed.
I exported 3 minutes of smooth scrolling text clip. Add it back to a new project and export to another 60fps clip (1080p). I couldn't see any lag.
If you confirmed that still happen, please try share the project and the media files (on DropBox, Google Drive etc.) to us so we can investigate.
Edit: It might because of the player. I've tested on one machine, playback in WMP was laggy but fine in VLC. On another machine both players are OK.