The single most disappointing fact about (more or less) all text editors on the market today is how god awful their performance is. For most text editors, and when I say most I really do mean _most_, you can very easily start seeing noticeable lag and stuttering when making modifications, or even outright INPUT LAG when entering text. For very tiny buffers <1kB it's a rare occurrence (although bad editors lag there too), but once you start crossing the 10kB size it's dead obvious. For editing buffers >1MB, 99% of them are unusable due to a) writes taking SECONDS (how?) b) scrolling/using the buffer physically lagging out the editor itself. Which is really basic functionality that editors should be able to handle since it's rather trivial to come across a multiMB json/config file. Try a simple benchmark
cd /tmp && dd if=/dev/random of=big_file bs=4096 count=10000
[editor of choice big_file]