IsVendor could be changed to use a single regexp

[smola]

IsVendor is using the substring library. It does an Or with dozens of Go regexps. Instead of that, we could check if using a single Go regexp with | is faster.

[bzz]

Thank you for a suggestion!

Indeed, we do exactly this kind of optimization in the latest-added heuristics strategy, but never actually got to measure the performance benefit of that.

Let me know if you are seeing IsVendor being slow in actual application and we'll gauge priority of this one!