Coinbase, one of the largest cryptocurrency exchanges, said that service has been slowed by record user demand as the price of bitcoin surged to an all-time high.

The online exchange’s engineers are working on the issue, according to a posting on its website.

The number of accounts at Coinbase, which serves as a platform for trading bitcoin and rivals such as ethereum, had almost tripled to 13 million in the past year, Bespoke Investment Group LLC said earlier.

The exchange has grappled with performance issues in the past, including outages, slow load times and a June flash crash in ether, the second most valuable virtual coin.