I do not think that the problem with UNISWAP is the speed, rather the transaction fees.
Transactions are conducted by smart contracts that require a lot of fees, and the accounts system makes updating them requires some time.
The speed of response of website is if there is an attack on the site, which is not often.
Have you ever tried Uniswap on a 1gb ram phone or 2gb ram and see it's lags .
Just visit
www.kingex.xyz/ex and
www.kingex.xyz and compare it .
The transaction fees is based on Ethereum.