@ Mr Blaazen
Of course, you need binary compiler to compile newer version of fpc from sources. There is a rule that you should use the latest stable fpc (or another newer SVN). In this case, you should have fpc 2.4.4 and you can use it for compiling sources 2.5.1 to gain fpc-2.5.1. Then you install fpc 2.5.1 to your system (sudo make install) and you can use it to compile Lazarus.
I totally agree with you
I have updated to fpc-2.5.1.
Of course i have to install fpc-2.5.1 before Lazarus.
Now, everything is upgraded, i have recompiled my prog with that brand new fpc-2.5.1.
First change i see : miXimum compiled with fpc-2.4.2 was 5.0 megas.
Compiled with fpc-2.5.1 is 5.4 megas

Now for the run...
At the moment it plays without problem for 45 minutes. ( i cross my fingers

)
I hope that with the new fpc version it gonna resolve the problem i have noted with fpc-2.4.2 for Linux : after +- 1 hour playing, the application become slower, the timers are slower, everything respond slower.
The same code compiled with fpc-2.4.2 in Windows and OSX do not have that problem.
Thanks