diff --git a/src/ccsd/ccsd_space_orb_sub.irp.f b/src/ccsd/ccsd_space_orb_sub.irp.f
index d23073b8..3c9a2cfc 100644
--- a/src/ccsd/ccsd_space_orb_sub.irp.f
+++ b/src/ccsd/ccsd_space_orb_sub.irp.f
@@ -1549,19 +1549,12 @@ subroutine compute_B1_gam(nO,nV,t1,t2,B1,gam)
   double precision, allocatable :: X_vvvo(:,:,:), Y_vvvv(:,:,:)
   allocate(X_vvvo(nV,nV,nO), Y_vvvv(nV,nV,nV))
 !  ! B1(a,b,beta,gam) = cc_space_v_vvvv(a,b,beta,gam)
+  call gen_v_space(cc_nVa,cc_nVa,cc_nVa,1, cc_list_vir,cc_list_vir,cc_list_vir,(/ gam /), B1)
+
   !$omp parallel &
   !$omp shared(nO,nV,B1,cc_space_v_vvvv,cc_space_v_vvov,X_vvvo,gam) &
   !$omp private(a,b,beta) &
   !$omp default(none)
-  !$omp do
-    do beta = 1, nV
-      do b = 1, nV
-        do a = 1, nV
-          B1(a,b,beta) = cc_space_v_vvvv(a,b,beta,gam)
-        enddo
-      enddo
-    enddo
-  !$omp end do nowait
   do i = 1, nO
     !$omp do
       do b = 1, nV
@@ -1569,7 +1562,7 @@ subroutine compute_B1_gam(nO,nV,t1,t2,B1,gam)
           X_vvvo(a,b,i) = cc_space_v_vvov(a,b,i,gam)
         enddo
       enddo
-    !$omp end do nowait
+    !$omp end do
   enddo
   !$omp end parallel
 
diff --git a/src/utils_cc/mo_integrals_cc.irp.f b/src/utils_cc/mo_integrals_cc.irp.f
index dafcf7af..2e7ecdd4 100644
--- a/src/utils_cc/mo_integrals_cc.irp.f
+++ b/src/utils_cc/mo_integrals_cc.irp.f
@@ -48,32 +48,86 @@ subroutine gen_v_space(n1,n2,n3,n4,list1,list2,list3,list4,v)
   integer                       :: i1,i2,i3,i4,idx1,idx2,idx3,idx4,k
 
   if (do_ao_cholesky) then
-    double precision, allocatable :: buffer(:,:,:)
-    !$OMP PARALLEL &
-    !$OMP SHARED(n1,n2,n3,n4,list1,list2,list3,list4,v,mo_num,cholesky_mo_transp,cholesky_ao_num) &
-    !$OMP PRIVATE(i1,i2,i3,i4,idx1,idx2,idx3,idx4,k,buffer)&
-    !$OMP DEFAULT(NONE)
-    allocate(buffer(mo_num,mo_num,mo_num))
+    double precision, allocatable :: buffer(:,:,:,:)
+    double precision, allocatable :: v1(:,:,:), v2(:,:,:)
+    allocate(v1(cholesky_ao_num,n1,n3), v2(cholesky_ao_num,n2,n4))
+    allocate(buffer(n1,n3,n2,n4))
+
+    !$OMP PARALLEL PRIVATE(i1,i2,i3,i4,idx1,idx2,idx3,idx4,k)
     !$OMP DO
-    do i4 = 1, n4
+    do i3=1,n3
+      idx3 = list3(i3)
+      do i1=1,n1
+        idx1 = list1(i1)
+        do k=1,cholesky_ao_num
+          v1(k,i1,i3) = cholesky_mo_transp(k,idx1,idx3)
+        enddo
+      enddo
+    enddo
+    !$OMP END DO NOWAIT
+
+    !$OMP DO
+    do i4=1,n4
       idx4 = list4(i4)
-      call dgemm('T','N', mo_num*mo_num, mo_num, cholesky_ao_num, 1.d0, &
-         cholesky_mo_transp, cholesky_ao_num, &
-         cholesky_mo_transp(1,1,idx4), cholesky_ao_num, 0.d0, buffer, mo_num*mo_num)
-      do i2 = 1, n2
+      do i2=1,n2
         idx2 = list2(i2)
-        do i3 = 1, n3
-          idx3 = list3(i3)
+        do k=1,cholesky_ao_num
+          v2(k,i2,i4) = cholesky_mo_transp(k,idx2,idx4)
+        enddo
+      enddo
+    enddo
+    !$OMP END DO NOWAIT
+
+    !$OMP BARRIER
+    !$OMP END PARALLEL
+
+    call dgemm('T','N', n1*n3, n2*n4, cholesky_ao_num, 1.d0, &
+         v1, cholesky_ao_num, &
+         v2, cholesky_ao_num, 0.d0, buffer, n1*n3)
+
+    deallocate(v1,v2)
+
+    !$OMP PARALLEL DO PRIVATE(i1,i2,i3,i4)
+    do i4 = 1, n4
+      do i3 = 1, n3
+        do i2 = 1, n2
           do i1 = 1, n1
-            idx1 = list1(i1)
-            v(i1,i2,i3,i4) = buffer(idx1,idx3,idx2)
+            v(i1,i2,i3,i4) = buffer(i1,i3,i2,i4)
           enddo
         enddo
       enddo
     enddo
-    !$OMP END DO
-    deallocate(buffer)
-    !$OMP END PARALLEL
+    !$OMP END PARALLEL DO
+
+!    !$OMP PARALLEL &
+!    !$OMP SHARED(n1,n2,n3,n4,list1,list2,list3,list4,v,cholesky_mo_transp,cholesky_ao_num,v1) &
+!    !$OMP PRIVATE(i1,i2,i3,i4,idx1,idx2,idx3,idx4,k,buffer,v2)&
+!    !$OMP DEFAULT(NONE)
+!    allocate(buffer(n1,n3,n2), v2(cholesky_ao_num,n2))
+!    !$OMP DO
+!    do i4 = 1, n4
+!      idx4 = list4(i4)
+!      do i2=1,n2
+!        idx2 = list2(i2)
+!        do k=1,cholesky_ao_num
+!          v2(k,i2) = cholesky_mo_transp(k,idx2,idx4)
+!        enddo
+!      enddo
+!      call dgemm('T','N', n1*n3, n2, cholesky_ao_num, 1.d0, &
+!         v1, cholesky_ao_num, &
+!         v2, cholesky_ao_num, 0.d0, buffer, n1*n3)
+!      do i3 = 1, n3
+!        do i2 = 1, n2
+!          do i1 = 1, n1
+!            v(i1,i2,i3,i4) = buffer(i1,i3,i2)
+!          enddo
+!        enddo
+!      enddo
+!    enddo
+!    !$OMP END DO
+!    deallocate(buffer, v2)
+!    !$OMP END PARALLEL
+!    deallocate(v1)
 
   else
     double precision              :: get_two_e_integral
@@ -112,6 +166,7 @@ BEGIN_PROVIDER [double precision, cc_space_v, (mo_num,mo_num,mo_num,mo_num)]
   if (do_ao_cholesky) then
     integer                       :: i1,i2,i3,i4
     double precision, allocatable :: buffer(:,:,:)
+    call set_multiple_levels_omp(.False.)
     !$OMP PARALLEL &
     !$OMP SHARED(cc_space_v,mo_num,cholesky_mo_transp,cholesky_ao_num) &
     !$OMP PRIVATE(i1,i2,i3,i4,k,buffer)&