I have been using the BareTail for quite some time for viewing large logs (some GBs) and it is working very well is very fast. There is a free version and a commercial Pro version.
They say that it has
- Real-time file
- Optimised real-time viewing engine View files of any size (> 2GB)
- Scroll to any point in the whole file instantly
- View files over a network
- Configurable line wrapping
- Configurable TAB expansion
- Configurable font, including spacing and offset to maximise use of screen space
Another alternative is Far Manager. Viewing a several GBs file is no problem (little memory footprint), but attempting to open the text file in the Editing mode might take several GBs of RAM, so be aware of that. I am not aware of the file size limit that can be viewed/edited in Far.