diff --git a/CMakeLists.txt b/CMakeLists.txt
index 4ab55a935..8670a37b6 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -521,8 +521,8 @@ elseif (Fortran_COMPILER_NAME MATCHES "g77")
 else (Fortran_COMPILER_NAME MATCHES "gfortran.*")
   message ("CMAKE_Fortran_COMPILER full path: " ${CMAKE_Fortran_COMPILER})
   message ("Fortran compiler: " ${Fortran_COMPILER_NAME})
-  message ("No optimized Fortran compiler flags are known, we just try -O2...")
-  set (CMAKE_Fortran_FLAGS_RELEASE "${CMAKE_Fortran_FLAGS_RELEASE} -O2 ${General_FFLAGS}")
+  message ("No optimized Fortran compiler flags are known, we just try -O3...")
+  set (CMAKE_Fortran_FLAGS_RELEASE "${CMAKE_Fortran_FLAGS_RELEASE} -O3 ${General_FFLAGS}")
   set (CMAKE_Fortran_FLAGS_DEBUG   "${CMAKE_Fortran_FLAGS_DEBUG} -fbounds-check ${General_FFLAGS}")
 endif (Fortran_COMPILER_NAME MATCHES "gfortran.*")
 
diff --git a/lib/Makefile.jtsdk b/lib/Makefile.jtsdk
index bc2546bdf..cde1126db 100644
--- a/lib/Makefile.jtsdk
+++ b/lib/Makefile.jtsdk
@@ -13,8 +13,8 @@ CC  = c:/JTSDK/Qt5/Tools/mingw48_32/bin/gcc
 FC = c:/JTSDK/Qt5/Tools/mingw48_32/bin/gfortran
 CXX = c:/JTSDK/Qt5/Tools/mingw48_32/bin/g++
 
-FFLAGS = -O2 -Wall -fno-second-underscore -DWIN32
-CFLAGS = -I. -fbounds-check -mno-stack-arg-probe -DWIN32
+FFLAGS = -O3 -Wall -Wno-conversion -fno-second-underscore -DWIN32
+CFLAGS = -I. -mno-stack-arg-probe -DWIN32
 
 # Default rules
 %.o: %.c
diff --git a/lib/Makefile.linux b/lib/Makefile.linux
index ecb8d4989..923eff4fc 100644
--- a/lib/Makefile.linux
+++ b/lib/Makefile.linux
@@ -12,8 +12,7 @@ CP = cp
 RANLIB = ranlib
 RM = rm -f
 
-FFLAGS = -O2 -fbounds-check -Wall -Wno-conversion -fno-second-underscore \
-       -fPIE -DUNIX
+FFLAGS = -O3 -funroll-loops -Wall -Wno-conversion -fno-second-underscore -DUNIX
 CFLAGS = -I. -fbounds-check -fPIE
 
 # Default rules
@@ -37,9 +36,9 @@ OBJS1 = astrosub.o astro0.o astro.o tm2.o sun.o moondop.o coord.o tmoonsub.o \
 	grid2k.o unpacktext.o getpfx2.o packmsg.o deg2grid.o \
 	packtext.o getpfx1.o packcall.o k2grid.o packgrid.o \
 	nchar.o four2a.o grid2deg.o pfxdump.o wisdom.o \
-	symspec.o analytic.o db.o genjt9.o \
+	symspec.o analytic.o db.o genjt9.o jt9fano.o \
 	packbits.o unpackbits.o encode232.o interleave9.o \
-	entail.o fano232.o gran.o sync9.o decode9.o \
+	entail.o fano232.o gran.o sync9.o decjt9.o \
 	fil3.o decoder.o grid2n.o n2grid.o timer.o \
 	softsym.o peakdt9.o getlags.o afc9.o fchisq.o \
 	twkfreq.o downsam9.o symspec2.o ipcomm.o sleep_msec.o \
@@ -59,7 +58,7 @@ libjt9.a: $(OBJS1)
 OBJS2 = jt9.o jt9a.o jt9b.o jt9c.o
 
 jt9: 	$(OBJS2) libjt9.a 
-	$(CXX) -o jt9 $(OBJS2) -L. -ljt9 -lQt5Core -lfftw3f `$(FC) -print-file-name=libgfortran.so`
+	$(CXX) -o jt9 $(OBJS2) -L. -ljt9 -lQt5Core -lfftw3f_threads -lfftw3f `$(FC) -print-file-name=libgfortran.so`
 	$(MKDIR) -p $(EXE_DIR)
 	$(CP) jt9 $(EXE_DIR)
 
diff --git a/lib/decjt9.f90 b/lib/decjt9.f90
index d39fdc901..f916b8c96 100644
--- a/lib/decjt9.f90
+++ b/lib/decjt9.f90
@@ -46,9 +46,13 @@ subroutine decjt9(ss,id2,nutc,nfqso,newdat,npts8,nfa,nfsplit,nfb,ntol,  &
         ccflim=2.7
      endif
      if(ndepth.ge.3 .or. nqd.eq.1) then
-        limit=50000
+        limit=30000
         ccflim=2.5
      endif
+     if(nagain.ne.0) then
+        limit=100000
+        ccflim=2.4
+     endif
      ccfok=.false.
 
      if(nqd.eq.1) then
diff --git a/lib/downsam9.f90 b/lib/downsam9.f90
index ac9e1855a..9096f90f2 100644
--- a/lib/downsam9.f90
+++ b/lib/downsam9.f90
@@ -1,7 +1,7 @@
 subroutine downsam9(id2,npts8,nsps8,newdat,nspsd,fpk,c2,nz2)
 
-!Downsample from id2() into C2() so as to yield nspsd samples per symbol, 
-!mixing from fpk down to zero frequency.
+!Downsample from id2() into c2() so as to yield nspsd samples per symbol, 
+!mixing from fpk down to zero frequency.  The downsample factor is 432.
 
   use, intrinsic :: iso_c_binding
   use FFTW3
@@ -9,23 +9,23 @@ subroutine downsam9(id2,npts8,nsps8,newdat,nspsd,fpk,c2,nz2)
   include 'constants.f90'
 !  parameter (NMAX1=1024*1920)
   parameter (NMAX1=884736)
-  type(C_PTR) :: plan                       !Pointers plan for big FFT
+  type(C_PTR) :: plan                        !Pointers plan for big FFT
   integer*2 id2(0:8*npts8-1)
   real*4 x1(0:NMAX1-1)
   complex c1(0:NMAX1/2)
-  complex c2(0:4096-1)
+  complex c2(0:1440-1)
   real s(5000)
   logical first
   common/patience/npatience,nthreads
   data first/.true./
   save plan,first
 
-  nfft1=1024*nsps8                          !Forward FFT length
+  nfft1=604800                               !Forward FFT length
   df1=12000.0/nfft1
   npts=8*npts8
 
   if(newdat.eq.1) then
-     fac=6.963e-6                             !Why this weird constant?
+     fac=6.963e-6                            !Why this weird constant?
      do i=0,npts-1
         x1(i)=fac*id2(i)
      enddo
diff --git a/lib/softsym.f90 b/lib/softsym.f90
index 2e7c32ffa..cc43d6cc5 100644
--- a/lib/softsym.f90
+++ b/lib/softsym.f90
@@ -3,9 +3,9 @@ subroutine softsym(id2,npts8,nsps8,newdat,fpk,syncpk,snrdb,xdt,        &
 
 ! Compute the soft symbols
 
-  complex c2(0:4096-1)
-  complex c3(0:4096-1)
-  complex c5(0:4096-1)
+  complex c2(0:1440-1)
+  complex c3(0:1440-1)
+  complex c5(0:1440-1)
   real a(3)
   integer*1 i1SoftSymbolsScrambled(207)
   integer*1 i1SoftSymbols(207)