"It’s commonly understood that new blocks are added to the blockchain approximately every 10 minutes. What some fail to realise is that this doesn’t necessarily mean that your BTC transaction will be included in that block!
When you initiate a BTC transaction, it heads off to a place called the mempool. Think of it as a ‘waiting room’ for transactions ready to be processed and added to the block. But because BTC has a block size limit of 1MB of data, a block only has the capacity to include around 2,000 transactions, give or take a few 100, as the below chart confirms".
How (S)Low Can You Go? Why BTC Sucks as Cash!
Written by Vee Tardrew
on 21 September 2020
https://blog.bitstocks.com/how-slow-can-you-go-why-btc-sucks-as-cash