QTGMC and SetMTmode Problem please Help me out

[wsh]

Hello guys
I just started to learn encoding with avisynth, it is very confusing and frustrating but result is very much rewarding.
I'm from Korea so please pardon my inadequate English.
I will just go straight toward my problems.

Source
Non-anime
DVD
NTSC
Interlaced (100% in dgindex, however megui analyse tells me that this source is mostly interlaced, where bring me the big question mark. )
Bottom field first


Computer spec
Intel I5-2500
8 gigabyte of memory
GTX 5600ti Nvidia
Win 7 64 bit (although using 32bit avisynth 2.6 and replaced with 2.6 MT *by sett)

Script
------------------------------------------------------------------
SetMemoryMax (800) ###<-- first start with 1024
SetMtMode(5,12) ###<-- i'm not sure max threads of I5-2500 CPU but when i used 12 threads initial CPU usage was nearly 100%

LoadPlugin("C:\Program Files (x86)\MeGUI_2153_x86\tools\dgindex\DGDecode.dll")
DGDecode_mpeg2source("D:\VTS_01_1.d2v")
import("C:\Program Files (x86)\AviSynth 2.5\plugins\FastDegrain.avs")

setmtmode(2)
QTGMC( Preset="slower", SourceMatch=3, Lossless=2, Sharpness=0.3, TR2=3,
\NoiseProcess=2, GrainRestore=0.4, NoiseRestore=0.2, Sigma=2,
\NoiseDeint="Generate", StabilizeNoise=true, EdiThreads=6) ######<---edithreads=6 is that correct?

fastdegrain(blksize=16)

lsfmod(defaults="slow")

yahr()
--------------------------------------------------------------------

encoded with megui(10bit version of x264) CFR 19 deblocking(-1,-1)

I don't get any errors but there are several problems.

Beginning part of encoding shows no problem
Processing rate of 13 fps and CPU usage @ 95~100%, estimate time remaining was 5hrs

After 20 mins passed
Processing rate of 8 fps and Cpu usage @ 70~80%

After 1hr passed
Processing rate of 2fps and CPU usage @ 50% , now estimate time remaining is 15hrs...

fps is keep dropping ....

Here are my main questions..

1) Can any one give me an advise how to properly use MtSetMode in this script?

2) Did I choose right de-interlacer? In other words how can I know that my source is pure interlace not blended nor hybrid, since megui said it is mostly interlaced

3) Does QTGMC works fine with Blended or Hybrid source? (Preview images shows that QTGMC is much better than using Yadif, TIVTC or Tdient)

4) Did I do too much denoising and sharpening? (wasn't satisfied with QTGMC degrain, but i'm losing detail with fastdegrain and lsfmod)

Thanks for reading my long and boring question, any help would be greatly appreciated.

============================================================================
PS : This is somewhat irrelevant to previous questions but..
Is this an efficient script?

setmemorymax(1024)
setmtmode(5,12)

LoadPlugin("C:\Program Files (x86)\MeGUI_2153_x86\tools\dgindex\DGDecode.dll")
DGDecode_mpeg2source("D:\aiai.d2v")
import("C:\Program Files (x86)\AviSynth 2.5\plugins\FastDegrain_mod16.avs")

SetMtmode(2)
Tcomb(mode=0,fthreshl=8,othreshl=8)
MergeChroma(Bifrost(interlaced=true,altclip=LUTDeRainbow()))
QTGMC( Preset="slower", SourceMatch=3, Lossless=2, Sharpness=0.3, TR2=3,
\NoiseProcess=2, GrainRestore=0.4, NoiseRestore=0.2, Sigma=2,
\NoiseDeint="Generate", StabilizeNoise=true, EdiThreads=6)
MergeChroma(awarpsharp2(depth=32))

MCTD(settings="high",shmode=5,strength=1000,enhance=true,dbF ="""FastDegrain(degrain=1,blksize=16).GradFun3(lsb=true, lsb_in=true)""")
SmoothTweak16(saturation=1.5,dither=0)
SmoothLevels16(16, 1.000, 235, 0, 255,limiter=2,smooth=100,Lmode=1,Ecurve=1,dither=100)
ditherpost()
lsfmod(defaults="slow")