269KB PHP file slows Quanta

Hi,
I have ~300KB files (300KB per file, uh. 5000 lines),  joyfully mixing PHP, 
HTML and Javascript in the same file.
My job is to clean them up. Huge job....
But I have problem when switching from tab to tab when file are so big.
Quanta freezes during about 15 or 20 seconds before I may edit the file.

I guess the editor is re parsing that ugly file each time I leave and come 
back to the tab.

Do you have a similar behaviour?

Quanta & KDE 3.5.7 Debian packaged.