On Sat, Sep 5, 2015 at 12:00 PM, Hector Sánchez hector@... [firebird-support] <firebird-support@yahoogroups.com> wrote:

I discovered something else quite interesting:

I realized both IB and FB dbs have pagebuffers set to 100.000. I changed FB to 0 and now it works like I expected!!..Same query now completes on FB on 50 sec. It seems this is the problem although I don't understand why.

Nevertheless, I'll try on a physical machine as you and Carlos suggest and see how it behaves.

Very odd.   Could you collect the performance stats for the query on the two systems? Specifically, I'd like to know how much physical I/O each did - that's reported as Reads and Writes.  Fetches and Marks don't matter here. 

Cheers,

Ann

On another system I worked on we realized as the cache got very large that a totally fair LRU was taking up a significant fraction of the CPU load.  That might be what you're seeing.