GOP Mode playback

[ioncube]

So I used Solveigmm to split a file at various timezones into one single file, it creates a following file used by its batch utility:

<timeline>
	 <group name="d:\out.wmv" mode="trimming">
		<track video="1" audio="1" accuracy="gop" >
			 <clip src="J:\System\input.wmv" start="260066462" stop="419211656" timeFormat="100ns_units" />
			 <clip src="J:\System\input.wmv" start="2453770000" stop="2725621701" timeFormat="100ns_units" />
			 <clip src="J:\System\input.wmv" start="3671354172" stop="3837616757" timeFormat="100ns_units" />
		</track>
	 </group>
	
</timeline>

This line <track video="1" audio="1" accuracy="gop" > can be changed for Frame accuracy mode <track video="1" audio="1" accuracy="frame" >
I use FA mode it takes a huge time for Soleigmm to perform trimming while in GOP mode I take just a fraction of a minute. However there is not much size variation in either method. Now the question is the VLC playback is extremely distorted/sluggish while playing a file trimmed with GOP mode but this file runs smooth on WMP? I don't want to use FA mode because of its time consumption also after waiting for hours Solveigmm may throw a nasty error.
Second question is is there an x264 syntax that accepts a timeline as above & cut scenes which can then be joined?