Most of platforms require about 12 confirmations on ETH network to credit users' balance so it takes much lesser than 10 - 30 minutes with BTC transactions (platforms tend to require from 1 to 3 confirmations with BTC).
It does not only relate to the size of transactions, but it relates to the confirmations. The more confirmations one transactions have on networks, the less risks for transactions and people who have trade deals with those transactions.