I personally haven’t used this converter but considering that you’re converting a digital signal (HDMI) to an analog signal (VGA), using one of these converters is definitely going to introduce some lag. Even the HD Box Pro, which converts analog YPbPr signals to VGA is confirmed to have 2 frames of lag, and that’s analog to analog. To this date, I think the only lagless converter solutions are from the HDFury line.
The HD box pro effectively lags, but this may be due to the upscaling process.
The Lenkeng, like the HDfury doesn’t upscale nor downscale, it simply converts from hdmi to vga.
It may not be as good as the costly HDfury whose quality was already confirmed, but I doubt it would score far behind.