New preview mode slower on win xp 64 bit

On a Core 2 duo T9300 with 4 Go ram with windows xp 64 bit sp2.
- go in option, choose "Show elapsed rendering time" and the legacy Progressive preview)
- select a filter a ( i tried Plastered tiles, 5216.html and = tracks =, 5358.html)
- write the time needed to render and try to take the time for first pass.
- select any other filter b
- go back in options and select 3, 4 or 5 passes in progressive previews
- select filter a again and look at the time needed to render the first pass and to complete, it's longer than legacy mode.
Do that procedure with and without cache preservation for preview as said on beta 3 page. The problem is the same, first pass and full rendering are slower and first pass in new preview mode is really pixelated (that's normal but it makes the new preview mode useless, and worse as the old filterforge 2 on 64 bit windows xp). On some filters, first pass is about the same but never 16 time faster as it should be.

I have the same problem.I try now the filter photo/real contrast.with 4 passes it need 3.09 - 3.10 sec.with off it need 0.77- 0.78 sec.

maybe this is a CPU cache problem, the large calc steps cause lots cache stalls.
maybe can speedup when 1 line calc complete, 4. line complete etc.

I have done a filter that can do high quality sharpen(hair, grass and trees look lots better when view a 10 megapixel image with 70-100% View), skin smooth, gamma and contrast enhancements, by use of band filter to boost or lower a band, assemble out of blur filters.

I use lowpass without gaussian, i guess this is faster as with gaussian.highpass filter i not use, because it give grey output and is not faster.i subtract for highpass the original image.

only problem its very slow then , it need when i release a slider or choose a preset, before any pixel is draw 3 sec.I have a I5 760 and win64.the whole effect is draw in 11 sec with off and with 4 passes it need 45 sec now.

I have currently no FF, only beta Version.I cannot upload the filter, to share.maybe somebody can help to do that better.