[firebird-support] Firebird 2.5 linux udf executing time much slower then FB 1.5

[biuro]

Hello
  
 I test Firebird 2.5. Some of my procedures work slower then with FB1.5 but 
mostly in linux. 
 I discovered that one of the reason was slower execute of udf .
 On windows (local test) the difference between FB2.5 and 1.5 was acceptable.
  
 Firebird.2.5.2 Classic (Superserver too) 64 bit (tested with binary and also 
with compiled source)
 buffers 2048, FW off
 Linux CentOS release 6.2 (Final),  kernel 2.6.32-220.7.1.el6.x86_64, Intel(R) 
Xeon(R) CPU E31220 @ 3.10GHz
client IbExpert

 I tested it with two servers -second red hat.
  
 I created very simple udf to test 
 with one function: int fn_one() { return 1;}
  
 I declared this function as MD_ONE
 DECLARE EXTERNAL FUNCTION MD_ONE RETURNS INTEGER BY VALUE ENTRY_POINT 'fn_one' 
MODULE_NAME 'udflib';
  
 I created procedure 
 CREATE PROCEDURE XX_2( S INTEGER, C INTEGER) RETURNS ( R INTEGER)
AS
  declare d integer;
begin
  r = s;
  while (r < c) do begin
    d = md_one(); d = md_one(); d = md_one();  d = md_one(); d = md_one(); d = 
md_one();
    d = md_one(); d = md_one(); d = md_one();  d = md_one(); d = md_one(); d = 
md_one();
    r = r + 1;
    suspend;
  end
end
 and executed it 
 select count(*) from xx_2(0, 80000)
 
Average execute time was over 3.5 sec
  
 In FB1.5 it last about 0.2 sec
  
 The more udf functions is executed the diffrence is biger. 
  
 I now that loop is big but in practice there are construction like that
  
 for select  from xx do begin
   for select  from yy do begin
      for select  from zz do begin
        d= md_one;
      end
   end
 end
   
 I need advice - what can I do to speed up execution.
 Is it a problem with configuration FB or linux ?
  
 Regards,
   Mariusz Duch