Measuring the Bruins’ performance last night in Game 3 of the Eastern Conference quarterfinal series, yes, the No. 1 line of Milan Lucic, David Krejci and Nathan Horton was good enough to break the hearts of Toronto Maple Leafs fans — piling up two goals and six assists in a 5-2 victory.

These guys were a joy to watch.

And yes, we should note that the fourth line was also very, very good. Good enough that with barely a minute left to play and the score 4-2, coach Claude Julien had the trio on the ice and it delivered a brilliant, territory-controlling shift, with Shawn Thornton especially strong along the walls to keep the puck deep in the Toronto end.

The No. 2 line? Well, Patrice Bergeron & Co produced zero points, but generally played pretty well as a line, although Tyler Seguin, looking nervous, had a dreadful night trying to pass, receive or shoot the puck.

And that leaves, of course, the B’s beleaguered third line, the source of so much consternation for so much of this season. It was a threesome which did not look good at all in Game 2 of this series, with Jaromir Jagr especially seeming slow and disinterested.

But that all changed last night, and the terrific play of the third line ought to be viewed as great news by Bruins fans — evidence, maybe, that the team may get back to rolling four strong and effective lines, an attribute crucial to the Stanley Cup drive two years ago.

“David’s line has been great all year, and Bergy’s, and you can’t say enough about Soupie’s (Greg Campbell’s No. 4) line,” third-liner Rich Peverley said. “Hopefully we can produce when it matters.”