As I understand it, coinhive uses Monero, a crytocurrency that is hard to mine on GPUs.
From coinhive.com:
Monero is different. To mine Monero, you have to calculate hashes with an algorithm called Cryptonight. This algorithm is very compute heavy and – while overall pretty slow – was designed to run well on consumer CPUs.
There are solutions to run the Cryptonight algorithm on a GPU instead, but the benefit is about 2x, not 10000x like for other algorithms used by Bitcoin or Ethereum. This makes Cryptonight a nice target for JavaScript and the Browser.
Of course, when running through JavaScript performance still takes a bit of a toll, but it's not that bad. Our miner uses WebAssembly and runs with about 65% of the performance of a native Miner. For an Intel i7 CPU (one of the fastest desktop CPUs) you should see a hashrate of about 90h/s. A native miner would get to 140h/s.
From coinhive.com: Monero is different. To mine Monero, you have to calculate hashes with an algorithm called Cryptonight. This algorithm is very compute heavy and – while overall pretty slow – was designed to run well on consumer CPUs.
There are solutions to run the Cryptonight algorithm on a GPU instead, but the benefit is about 2x, not 10000x like for other algorithms used by Bitcoin or Ethereum. This makes Cryptonight a nice target for JavaScript and the Browser.
Of course, when running through JavaScript performance still takes a bit of a toll, but it's not that bad. Our miner uses WebAssembly and runs with about 65% of the performance of a native Miner. For an Intel i7 CPU (one of the fastest desktop CPUs) you should see a hashrate of about 90h/s. A native miner would get to 140h/s.