diff --git a/src/cipsi/run_pt2_slave.irp.f b/src/cipsi/run_pt2_slave.irp.f
index 731e40ac..f9171a42 100644
--- a/src/cipsi/run_pt2_slave.irp.f
+++ b/src/cipsi/run_pt2_slave.irp.f
@@ -31,11 +31,11 @@ subroutine run_pt2_slave(thread,iproc,energy)
 
   double precision, intent(in)    :: energy(N_states_diag)
   integer,  intent(in)            :: thread, iproc
-!  if (N_det > 100000 ) then
-!    call run_pt2_slave_large(thread,iproc,energy)
-!  else
+  if (N_det > 100000 ) then
+    call run_pt2_slave_large(thread,iproc,energy)
+  else
     call run_pt2_slave_small(thread,iproc,energy)
-!  endif
+  endif
 end
 
 subroutine run_pt2_slave_small(thread,iproc,energy)
@@ -116,10 +116,10 @@ subroutine run_pt2_slave_small(thread,iproc,energy)
     do k=1,n_tasks
       call pt2_alloc(pt2_data(k),N_states)
       b%cur = 0
-      double precision :: time2
-      call wall_time(time2)
+!      double precision :: time2
+!      call wall_time(time2)
       call select_connected(i_generator(k),energy,pt2_data(k),b,subset(k),pt2_F(i_generator(k)))
-      call wall_time(time1)
+!      call wall_time(time1)
 !      print *,  i_generator(1), time1-time2, n_tasks, pt2_F(i_generator(1))
     enddo
     call wall_time(time1)
@@ -172,8 +172,8 @@ subroutine run_pt2_slave_large(thread,iproc,energy)
   integer                         :: rc, i
 
   integer                        :: worker_id, ctask, ltask
-  character*(512)                :: task
-  integer                        :: task_id(1)
+  character*(512), allocatable   :: task(:)
+  integer, allocatable           :: task_id(:)
 
   integer(ZMQ_PTR),external      :: new_zmq_to_qp_run_socket
   integer(ZMQ_PTR)               :: zmq_to_qp_run_socket
@@ -184,15 +184,16 @@ subroutine run_pt2_slave_large(thread,iproc,energy)
   type(selection_buffer) :: b
   logical :: done, buffer_ready
 
-  type(pt2_type) :: pt2_data
+  type(pt2_type), allocatable :: pt2_data(:)
   integer :: n_tasks, k, N
-  integer :: i_generator, subset
-
+  integer, allocatable :: i_generator(:), subset(:)
   integer :: bsize ! Size of selection buffers
   logical :: sending
   PROVIDE global_selection_buffer global_selection_buffer_lock
 
 
+  allocate(task_id(pt2_n_tasks_max), task(pt2_n_tasks_max))
+  allocate(pt2_data(pt2_n_tasks_max), i_generator(pt2_n_tasks_max), subset(pt2_n_tasks_max))
   zmq_to_qp_run_socket = new_zmq_to_qp_run_socket()
 
   integer, external :: connect_to_taskserver
@@ -211,6 +212,9 @@ subroutine run_pt2_slave_large(thread,iproc,energy)
   done = .False.
   do while (.not.done)
 
+    n_tasks = max(1,n_tasks)
+    n_tasks = min(pt2_n_tasks_max,n_tasks)
+
     integer, external :: get_tasks_from_taskserver
     if (get_tasks_from_taskserver(zmq_to_qp_run_socket,worker_id, task_id, task, n_tasks) == -1) then
       exit
@@ -221,11 +225,9 @@ subroutine run_pt2_slave_large(thread,iproc,energy)
     endif
     if (n_tasks == 0) exit
 
-    call sscanf_ddd(task, subset, i_generator, N)
-    if( pt2_F(i_generator) <= 0 .or. pt2_F(i_generator) > N_det ) then
-      print *,  irp_here
-      stop 'bug in selection'
-    endif
+    do k=1,n_tasks
+      call sscanf_ddd(task(k), subset(k), i_generator(k), N)
+    enddo
     if (b%N == 0) then
       ! Only first time
       bsize = min(N, (elec_alpha_num * (mo_num-elec_alpha_num))**2)
@@ -235,9 +237,14 @@ subroutine run_pt2_slave_large(thread,iproc,energy)
       ASSERT (b%N == bsize)
     endif
 
-    call pt2_alloc(pt2_data,N_states)
-    b%cur = 0
-    call select_connected(i_generator,energy,pt2_data,b,subset,pt2_F(i_generator))
+    double precision :: time0, time1
+    call wall_time(time0)
+    do k=1,n_tasks
+      call pt2_alloc(pt2_data(k),N_states)
+      b%cur = 0
+      call select_connected(i_generator(k),energy,pt2_data(k),b,subset(k),pt2_F(i_generator(k)))
+    enddo
+    call wall_time(time1)
 
     integer, external :: tasks_done_to_taskserver
     if (tasks_done_to_taskserver(zmq_to_qp_run_socket,worker_id,task_id,n_tasks) == -1) then
@@ -249,7 +256,7 @@ subroutine run_pt2_slave_large(thread,iproc,energy)
     call merge_selection_buffers(b,global_selection_buffer)
     b%cur=0
     call omp_unset_lock(global_selection_buffer_lock)
-    if ( iproc == 1 .or. i_generator < 100 .or. done) then
+    if ( iproc == 1 .or. i_generator(1) < 100 .or. done) then
       call omp_set_lock(global_selection_buffer_lock)
       call push_pt2_results_async_recv(zmq_socket_push,b%mini,sending)
       call push_pt2_results_async_send(zmq_socket_push, (/i_generator/), (/pt2_data/), global_selection_buffer, (/task_id/), 1,sending)
@@ -260,7 +267,13 @@ subroutine run_pt2_slave_large(thread,iproc,energy)
       call push_pt2_results_async_send(zmq_socket_push, (/i_generator/), (/pt2_data/), b, (/task_id/), 1,sending)
     endif
 
-    call pt2_dealloc(pt2_data)
+    do k=1,n_tasks
+      call pt2_dealloc(pt2_data(k))
+    enddo
+    b%cur=0
+!    ! Try to adjust n_tasks at least 5 seconds per task
+    n_tasks = min(2*n_tasks,int( dble(5*n_tasks) / (time1 - time0 + 1.d0)))
+    n_tasks = min(n_tasks, pt2_n_tasks_max)
   end do
   call push_pt2_results_async_recv(zmq_socket_push,b%mini,sending)