Speed comparison for some framebuffer drivers

Speed comparison for frambuffer drivers (uvesafb, vesafb) in two modes:
    - with 8bpp  (1680x1050-8@60) and
    - with 32bpp (1680x1050-32@60).


 *========*=============================================================================================*
 #   \    #                                        scroll method                                        #
 #     \  #-------------------------------*------------------------------*------------------------------*
 # mtrr  \# redraw                        | ypan                         | ywrap                        # 
 *--------*===============================*==============================*==============================*
 #        #                                       uvesafb                                               #
 #        #                                      ---------                                              #
 # 0      #                               #                              # (2.180s, --) @ (12.261s, fb) #
 # 2 (wb) # (15.010s, --) @ (58.550s, fb) # (2.180s, --) @ (12.155s, fb) # (2.180s, --) @ (12.157s, fb) #
 # 3 (wc) # (2.202s,  --) @ (4.230s,  --) # (1.011s, --) @ (6.715s,  -b) # (1.011s, --) @ (6.720s,  -b) #
 *========*=============================================================================================*
 #        #                                       vesafb                                                #
 #        #                                      --------                                               #
 # 0      #                               #                              #                              #
 # 2 (wb) #                               #                              # (3.181s, ??) @ (12.305s, ??) #
 # 3 (wc) # (2.256s,  ??) @ (4.312s,  ??) # (0.235s, ??) @               # (0.289s, ??) @ (6.762s,  ??) #
 *========*=============================================================================================*
 vga text console = (1.263s, --)

 where

    (`cat`_time, [forward_scroll_lag][backward_scroll_lag]) @ (  ...   )
                  8 bpp                                     @   32 bpp

    (TIMEs, [f-][b-]) @ (..)
        
        () @    before @ is measurements for 8bpp mode.
        @ ()    after @ is measurements for 32bpp mode.
        TIME    is real time for command `time cat kernel-parameters.txt`.
        f       means that forward scroll lags in `less` or `vim`.
        b       means that backward scroll lags in `less` or `vim`.
        -       means that scroll in corresponding direction does not lag.


Notes:
    - As expected 'ypan'/'ywrap' scroll methods are faster than 'redraw' for
      both 8bpp and 32bpp with mtrr=2. But with mtrr=3 for 32bpp unexpectedly
      'redraw' scroll method becomes the fastest. Though for 8bpp situation
      remains the same.
    - Also, that's strange, but i don't notice any scroll lag with 'redraw'
      scroll and mtrr=2 for 8bpp, though `cat` time for this mode is long
      enough.
    - results for vesafb is almost the same as for uvesafb, though `cat` time
      for 8bpp with mtrr=3 and 'ywrap'/'ypan' scroll is even lesser (and,
      also, suprisingly lesser, than for vga text console).
    - For mtrr=4 results are the same as for mtrr=2.