Grid Data Loading Best Performance Usage

Hello ,
I m using dhtmlx grid with csv loading but when i search grid source codes i noticed that grid converts csv to xml with a regex. I can imagine that this regex makes my grid rendering slower. I have a customer which has more then 50 ppl working in their call center with low cpu speed. They are not pleased with rendering speed of my grid. I think i have to change csv to xml or i dont know is json supported. I want to ask which rendering method is faster?

Loading from all supported data sources works the same.
To increase loading performance you can try to use SmartRendering mode … _rendering