open large file with C code: is it realy should be so slow?

[Dave Milter]

I have problem with emacs responsibility,
I work with large enough C header files,
and when I want to scroll it using mouse's wheel or
page (up|down) keys emacs stop react on any keys, like (ctrl+g),
and eats 100% of CPU's time during long period,
I wonder is this a bug, or expected behaviour?

My cpu frequnce is 2200.000MHz.

elp results are:

Function Name                                              Call Count
Elapsed Time  Average Time
=========================================================  ==========
============  ============
font-lock-fontify-region                                   387
14.909457999  0.0385257312
font-lock-default-fontify-region                           387
14.904738000  0.0385135348
font-lock-fontify-keywords-region                          387
14.469801     0.0373896666
font-lock-fontify-syntactically-region                     384
0.4169809999  0.0010858880
font-lock-unfontify-region                                 387
0.0036489999  9.428...e-06
font-lock-mode                                             17
0.0036209999  0.0002129999
font-lock-set-defaults                                     390
0.0035869999  9.197...e-06
font-lock-default-function                                 17
0.0033780000  0.0001987058
font-lock-mode-internal                                    3
0.00324       0.00108
font-lock-compile-keywords                                 3
0.002872      0.0009573333
font-lock-compile-keyword                                  60
0.0027359999  4.559...e-05
font-lock-extend-region-multiline                          387
0.0010560000  2.728...e-06
font-lock-default-unfontify-region                         387
0.0010289999  2.658...e-06
font-lock-extend-region-wholelines                         387
0.0008740000  2.258...e-06
font-lock-extend-jit-lock-region-after-change              103
0.0007060000  6.854...e-06
font-lock-turn-on-thing-lock                               3
0.00034       0.0001133333
font-lock-change-mode                                      5
0.000144      2.880...e-05
font-lock-eval-keywords                                    4
2.7e-05       6.75e-06
font-lock-value-in-major-mode                              8
9e-06         1.125e-06
cc-imenu-init                                              1
7e-06         7e-06
font-lock-append-text-property                             1
6e-06         6e-06
font-lock-choose-keywords                                  2
4.999...e-06  2.499...e-06


Version:

GNU Emacs 22.3.1 (i686-pc-linux-gnu, GTK+ Version 2.12.8)


I tried Visual C++ 6.0 under wine,
and gvim, and they works without any delays,
highlight syntax and allow scrolling.

If somebody wnat reproduce this behaviour,
here is link to source code with which I working:
http://www.atmel.com/dyn/resources/prod_documents/AT91Bootstrap1.10.zip
there are files in it like
include/AT91SAM9263_inc.h
it contains around 4000 lines of code,
most of which is comments or #define