Discord is generally snappy but nothing beats Telegram. It just feels like the only remaining desktop client that actually makes use of native OS facilities.

Plus there are scripts to back up the said channels. With Discord I haven't checked (but maybe there are as well).

So mostly (1) Telegram is still snappier and (2) Telegram was there first, more or less, at least on my own timeline of checking chat clients.

Discord is much much slower than the telegram client IMO