Rails 2.3/3.1 TimeZone calculation/parsing performace gap

Why does this code

500.times { Time.now.in_time_zone('Helsinki') }

take several seconds with Rails 3.1 while it takes only a split second in Rails 2.3 (both with Ruby 1.9.2-p290)?

I discovered this by searching for a cause for an extremely slow loading page开发者_JS百科 after upgrading from Rails 2.3 to 3.1.

Any ideas? Also, how to fix it? Haven't found a workaround yet.

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Okay, this was an issue in TZInfo and has been fixed now in the Rails 3.1.1