geek4377/scrapy — comment on commit ae6ba09f5db37e91f2e65bc56d33df2000285a8d
File:  line 0
By pablohoffman:

Parsing proxy url on *every* request adds some considerable overhead that I'm not sure it's worth. The idea is that if 'proxy' key was already present in request.meta, it was assumed to be have been populated properly - hence the if 'proxy' in request.meta: return.