I'm not sure your definition of big file. But, the last thing that I tried to edit a full Wikipedia dump (in 2014) the file was 65GB, and it was slow even in UltraEdit. I tried all the editors suggested at the time, including Sublime but notice that VS Code wasn't available at the time. People love their programming editors, but UltraEdit is much more than that. It was an editor for data manipulation. It was the best for managing what used to be considered big files before (and too many other features, including moving around columns of data like what you can do in Excel - try that on other editor), but now the bar for file size is much higher, and UltraEdit had not improved there. The fastest editor for big files according to my tests was EmEditor, and editor that like UltraEdit, is made for loading data files. However, EmEditor can load what in 2021 can be claimed to be big files. It can open filed of up to 248GB in the 32-bit version and 16TB in the 64-bits version of the platform. That (the 64-bits version) is what I call big files.

https://www.emeditor.com/text-editor-features/large-file-sup...