With each transaction, one more block is added to the chain and every block contains the information of all the previous blocks. Now as the system is coming to the mainstream or say more and more people are joining the network, the history of transactions is also increasing. This triggers the danger of buckling as each block has to carry the data of all the previous blocks.
Block Size, Transaction Speed
Initially, Bitcoin’s block was hard-capped at 1 MB which is somewhat equal to 2,020 transactions. But as you know, with the increasing interest of people in Bitcoin, there are chances that each coin will take part in an infinite number of transactions. Which means that there would be infinite records of transactions to be stored on each block.
With the increasing number of transactions, there’s a need for an increase in block sizes that exceeds any limit. Although Bitcoin has exceeded its hard cap limit and Ethereum does not have any cap limit, there’s still one issue left to be fixed i.e the time taken for a transaction to be processed. The more will be the size of the block, the more will the time taken by each transaction to be completed.