You could try:
| floats | floats := (1 to: 200000) collect: #asFloat. [ FloatPrintPolicy value: InexactFloatPrintPolicy new during: [ String new: 1500000 streamContents: [ :stream | floats do: [ :each | each printOn: stream ] ] ] ] timeToRun
=> 796 ms
I haven't looked at the Postgresql driver in detail, but I would guess that PostgresV2 reads from a String somewhere, which is slow unless care is taken, while psycopg probably does a binary read. That last thing can be done in Pharo as well, but not if the driver is text based somehow.
You are right: Pharo should definitively be in the same range as other dynamically typed languages. But dynamic languages are dangerous: user become lazy / ignorant about performance.
Thanks for pushing this.
+1 we need more people to profile and look at these aspects. I can tell you that we are all working like crazy to improve the system and I hope that one of these days we will have real regression tests. But well you know it takes a lot of time. Stef