I have been benchmarking performance of Count() for a collection. I am seeing that Core is a lot slower than the CLR.
Count() (Clr) | VM 8.138 | LAPTOP 4.847
Count() (Core) | VM 18.073 | LAPTOP 12.355
Count() with Predicate (Clr) | VM 275,516.47 | LAPTOP 183,284.90
Count() with Predicate (Core) | VM 307,900.18 | LAPTOP 217,629.30
The VM above is an Azure VM: Size: Standard D8s v3 (8 vcpus, 32 GB memory)
Benchmarks were done with BenchmarkDotNet.