I tried to see what SE is doing during this time, so I attached with gdb and took 2 back traces shown below.
Looks like it is writing to some debug file?
#3 0x0000000001fca31b in cmDebugWriter_DebugFile::writeFile(cmROStringT<char, 1, 30> const&, cmDebugFlags, int, cmROStringT<char, 1, 30> const&, char const*, unsigned long long) ()
(gdb) bt
#0 0x00007fdcd6ba777d in open64 () from /lib64/libc.so.6
#1 0x00007fdcd6b33490 in __GI__IO_file_fopen () from /lib64/libc.so.6
#2 0x00007fdcd6b26c14 in __fopen_internal () from /lib64/libc.so.6
#3 0x0000000001fca31b in cmDebugWriter_DebugFile::writeFile(cmROStringT<char, 1, 30> const&, cmDebugFlags, int, cmROStringT<char, 1, 30> const&, char const*, unsigned long long) ()
#4 0x0000000001fcdb32 in cmDebug::~cmDebug() ()
#5 0x0000000001fd4ac7 in dfprintf ()
#6 0x00000000007d0e81 in pdsay_op() ()
#7 0x00000000007af8f1 in pmethod_op() ()
#8 0x0000000000603552 in run_proc(int) ()
#9 0x0000000000603899 in run_proc_immediate2(m_s*, int, int, VSARGTYPE const*, int, int) [clone .isra.423] ()
#10 0x0000000000603a67 in run_proc_immediate(int, int, VSARGTYPE const*, int, int) ()
#11 0x0000000000838813 in se_call_event(filewindow_t*, unsigned int, int, int, VSARGTYPE const*, int) ()
#12 0x00007fdcddb0cc03 in QObject::event(QEvent*) ()
from /home/rbresali/pen/slickedit/se_26000100_linux64/bin/libQtCore.so.4
#13 0x00007fdcddeb986c in QWidget::event(QEvent*) ()
from /home/rbresali/pen/slickedit/se_26000100_linux64/bin/libQtGui.so.4
#14 0x00007fdcdde6adac in QApplicationPrivate::notify_helper(QObject*, QEvent*) ()
from /home/rbresali/pen/slickedit/se_26000100_linux64/bin/libQtGui.so.4
#15 0x00007fdcdde71523 in QApplication::notify(QObject*, QEvent*) ()
from /home/rbresali/pen/slickedit/se_26000100_linux64/bin/libQtGui.so.4
#16 0x00007fdcddaf5a7d in QCoreApplication::notifyInternal(QObject*, QEvent*) ()
from /home/rbresali/pen/slickedit/se_26000100_linux64/bin/libQtCore.so.4
#17 0x00007fdcddaf8695 in QCoreApplicationPrivate::sendPostedEvents(QObject*, int, QThreadData*) ()
from /home/rbresali/pen/slickedit/se_26000100_linux64/bin/libQtCore.so.4
#18 0x00007fdcddb21633 in postEventSourceDispatch(_GSource*, int (*)(void*), void*) ()
from /home/rbresali/pen/slickedit/se_26000100_linux64/bin/libQtCore.so.4
#19 0x00007fdcd63c4099 in g_main_context_dispatch () from /lib64/libglib-2.0.so.0
#20 0x00007fdcd63c43f8 in ?? () from /lib64/libglib-2.0.so.0
#21 0x00007fdcd63c44ac in g_main_context_iteration () from /lib64/libglib-2.0.so.0
#22 0x00007fdcddb21784 in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) ()
from /home/rbresali/pen/slickedit/se_26000100_linux64/bin/libQtCore.so.4
#23 0x00007fdcddf06d66 in QGuiEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) ()
from /home/rbresali/pen/slickedit/se_26000100_linux64/bin/libQtGui.so.4
#24 0x00007fdcddaf424f in QEventLoop::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) ()
from /home/rbresali/pen/slickedit/se_26000100_linux64/bin/libQtCore.so.4
#25 0x00007fdcddaf4555 in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) ()
from /home/rbresali/pen/slickedit/se_26000100_linux64/bin/libQtCore.so.4
#26 0x00007fdcddaf9599 in QCoreApplication::exec() ()
from /home/rbresali/pen/slickedit/se_26000100_linux64/bin/libQtCore.so.4
#27 0x00000000004c26fc in vmain(int, char**) ()
#28 0x0000000001b46599 in xmain ()
#29 0x0000000000467a69 in main ()
gdb) bt
#0 0x00007fdcd6ba777d in open64 () from /lib64/libc.so.6
#1 0x00007fdcd6b33490 in __GI__IO_file_fopen () from /lib64/libc.so.6
#2 0x00007fdcd6b26c14 in __fopen_internal () from /lib64/libc.so.6
#3 0x0000000001fca31b in cmDebugWriter_DebugFile::writeFile(cmROStringT<char, 1, 30> const&, cmDebugFlags, int, cmROStringT<char, 1, 30> const&, char const*, unsigned long long) ()
#4 0x0000000001fcdb32 in cmDebug::~cmDebug() ()
#5 0x0000000001fd4ac7 in dfprintf ()
#6 0x00000000007d0e81 in pdsay_op() ()
#7 0x00000000007af8f1 in pmethod_op() ()
#8 0x0000000000603552 in run_proc(int) ()
#9 0x0000000000603899 in run_proc_immediate2(m_s*, int, int, VSARGTYPE const*, int, int) [clone .isra.423] ()
#10 0x0000000000603a67 in run_proc_immediate(int, int, VSARGTYPE const*, int, int) ()
#11 0x0000000000838813 in se_call_event(filewindow_t*, unsigned int, int, int, VSARGTYPE const*, int) ()
#12 0x00007fdcddb0cc03 in QObject::event(QEvent*) ()
from /home/rbresali/pen/slickedit/se_26000100_linux64/bin/libQtCore.so.4
#13 0x00007fdcddeb986c in QWidget::event(QEvent*) ()
from /home/rbresali/pen/slickedit/se_26000100_linux64/bin/libQtGui.so.4
#14 0x00007fdcdde6adac in QApplicationPrivate::notify_helper(QObject*, QEvent*) ()
from /home/rbresali/pen/slickedit/se_26000100_linux64/bin/libQtGui.so.4
#15 0x00007fdcdde71523 in QApplication::notify(QObject*, QEvent*) ()
from /home/rbresali/pen/slickedit/se_26000100_linux64/bin/libQtGui.so.4
#16 0x00007fdcddaf5a7d in QCoreApplication::notifyInternal(QObject*, QEvent*) ()
from /home/rbresali/pen/slickedit/se_26000100_linux64/bin/libQtCore.so.4
#17 0x00007fdcddaf8695 in QCoreApplicationPrivate::sendPostedEvents(QObject*, int, QThreadData*) ()
from /home/rbresali/pen/slickedit/se_26000100_linux64/bin/libQtCore.so.4
#18 0x00007fdcddb21633 in postEventSourceDispatch(_GSource*, int (*)(void*), void*) ()
from /home/rbresali/pen/slickedit/se_26000100_linux64/bin/libQtCore.so.4
#19 0x00007fdcd63c4099 in g_main_context_dispatch () from /lib64/libglib-2.0.so.0
#20 0x00007fdcd63c43f8 in ?? () from /lib64/libglib-2.0.so.0
#21 0x00007fdcd63c44ac in g_main_context_iteration () from /lib64/libglib-2.0.so.0
#22 0x00007fdcddb21784 in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) ()
from /home/rbresali/pen/slickedit/se_26000100_linux64/bin/libQtCore.so.4
#23 0x00007fdcddf06d66 in QGuiEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) ()
from /home/rbresali/pen/slickedit/se_26000100_linux64/bin/libQtGui.so.4
#24 0x00007fdcddaf424f in QEventLoop::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) ()
from /home/rbresali/pen/slickedit/se_26000100_linux64/bin/libQtCore.so.4
#25 0x00007fdcddaf4555 in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) ()
from /home/rbresali/pen/slickedit/se_26000100_linux64/bin/libQtCore.so.4
#26 0x00007fdcddaf9599 in QCoreApplication::exec() ()
from /home/rbresali/pen/slickedit/se_26000100_linux64/bin/libQtCore.so.4
#27 0x00000000004c26fc in vmain(int, char**) ()
#28 0x0000000001b46599 in xmain ()
#29 0x0000000000467a69 in main ()