Performance tests

[KadekM]

• it would be good to see how are sequential and parallel crawlers doing... although for web requests it's gonna be IO bounded anyway 👎
• third parties won't be happy if we use them for testing, and the results won't be telling us much anyway... or will they? Need to think about it. 👎
• first goal should be ability to observe changes on macro level, at least rough idea if parallel crawling is still parallel and if it's still faster than sequential etc., some general sense of non-brokeness 👍