But about fast execution time, you have no problem on the exchange future is existing, the volume of coins there are traded in a way that fast execution are guaranteed. That is the reason you will noticed on most exchanges, almost all pairs are not there but just the common ones like BTCUSDT and ETHUSDT. On some exchanges, I see SOLUSDT.
I just checked the Deribit trades for the December futures and the perpetual swap. The volumes on perpetual contracts are several times higher than on futures.Here are the perpetual contracts (trade volumes are the second column).
And here are the futures.
If you have a small limit order sitting at the top of the book, then maybe there’s no difference. But a large order will take longer to fill because it requires more trades for execution.