bash tab auto-complete is too slow but it isn't with teraterm or putty

I'm using Ubuntu 18.04 and it got stuck in 1~2 seconds when I push the tab button for auto-completion.

I've been trying to resolve this problem but I couldn't make it. I even changed my computer to the new one but it has same problem.

One weird thing is that when I connect my ubuntu with ssh in other pc(using teraterm or putty or other pc's ubuntu), the problem is gone and works well.

I don't know why.. Could it be a network problem? My ubuntu pc is behind the firewall and proxy but my companies' ubuntu next to me works well.

Is there anything suspicious to you?

Here's what I've done for the problem

• Change the computer to the new one.
• sudo updatedb
• sudo apt install --reinstall bash-completion

And, I followed https://unix.stackexchange.com/a/185960 method to investigate this. But, when I push the tab button after set -x, it is stuck at the first place. I mean,

$ set -x
$ ls a<tab>
# got stuck like 2~3 second
output of `set -x`

# full output when I push tab with `set -x`
+ _init_completion -s
+ local exclude= flag outx errx inx OPTIND=1
+ getopts n:e:o:i:s flag -s
+ case $flag in
+ split=false
+ exclude+==
+ getopts n:e:o:i:s flag -s
+ COMPREPLY=()
+ local 'redir=@(?([0-9])<|?([0-9&])>?(>)|>&)'
+ _get_comp_words_by_ref -n '=<>&' cur prev words cword
+ local exclude flag i OPTIND=1
+ words=()
+ local cur cword words
+ upargs=()
+ upvars=()
+ local upargs upvars vcur vcword vprev vwords
+ getopts c:i:n:p:w: flag -n '=<>&' cur prev words cword
+ case $flag in
+ exclude='=<>&'
+ getopts c:i:n:p:w: flag -n '=<>&' cur prev words cword
+ [[ 6 -ge 3 ]]
+ case ${!OPTIND} in
+ vcur=cur
+ let 'OPTIND += 1'
+ [[ 6 -ge 4 ]]
+ case ${!OPTIND} in
+ vprev=prev
+ let 'OPTIND += 1'
+ [[ 6 -ge 5 ]]
+ case ${!OPTIND} in
+ vwords=words
+ let 'OPTIND += 1'
+ [[ 6 -ge 6 ]]
+ case ${!OPTIND} in
+ vcword=cword
+ let 'OPTIND += 1'
+ [[ 6 -ge 7 ]]
+ __get_cword_at_cursor_by_ref '=<>&' words cword cur
+ words=()
+ local cword words
+ __reassemble_comp_words_by_ref '=<>&' words cword
+ local exclude i j line ref
+ [[ -n =<>& ]]
+ exclude='=<>&'
+ printf -v cword %s 1
+ [[ -n =<>& ]]
+ line='ls '
+ (( i=0, j=0 ))
+ (( i < 2 ))
+ [[ 0 -gt 0 ]]
+ ref='words[0]'
+ printf -v 'words[0]' %s ls
+ line=' '
+ [[ 0 == 1 ]]
+ (( i++, j++ ))
+ (( i < 2 ))
+ [[ 1 -gt 0 ]]
+ [[ '' == +([=<>&]) ]]
+ ref='words[1]'
+ printf -v 'words[1]' %s ''
+ line=' '
+ [[ 1 == 1 ]]
+ printf -v cword %s 1
+ (( i++, j++ ))
+ (( i < 2 ))
+ [[ 2 == 1 ]]
+ local i cur index=3 'lead=ls '
+ [[ 3 -gt 0 ]]
+ [[ -n ls  ]]
+ [[ -n ls ]]
+ cur='ls '
+ (( i = 0 ))
+ (( i <= cword ))
+ [[ 3 -ge 2 ]]
+ [[ ls != \l\s ]]
+ [[ 0 -lt 1 ]]
+ local old_size=3
+ cur=' '
+ local new_size=1
+ index=1
+ (( ++i  ))
+ (( i <= cword ))
+ [[ 1 -ge 0 ]]
+ [[ '' != '' ]]
+ [[ 1 -lt 1 ]]
+ (( ++i  ))
+ (( i <= cword ))
+ [[ -n   ]]
+ [[ ! -n '' ]]
+ cur=
+ [[ 1 -lt 0 ]]
+ local words cword cur
+ _upvars -a2 words ls '' -v cword 1 -v cur ''
+ ((  10  ))
+ ((  10  ))
+ case $1 in
+ [[ -n 2 ]]
+ printf %d 2
+ [[ -n words ]]
+ unset -v words
+ eval 'words=("${@:3:2}")'
++ words=("${@:3:2}")
+ shift 4
+ ((  6  ))
+ case $1 in
+ [[ -n cword ]]
+ unset -v cword
+ eval 'cword="$3"'
++ cword=1
+ shift 3
+ ((  3  ))
+ case $1 in
+ [[ -n cur ]]
+ unset -v cur
+ eval 'cur="$3"'
++ cur=
+ shift 3
+ ((  0  ))
+ [[ -n cur ]]
+ upvars+=("$vcur")
+ upargs+=(-v $vcur "$cur")
+ [[ -n cword ]]
+ upvars+=("$vcword")
+ upargs+=(-v $vcword "$cword")
+ [[ -n prev ]]
+ [[ 1 -ge 1 ]]
+ upvars+=("$vprev")
+ upargs+=(-v $vprev "${words[cword - 1]}")
+ [[ -n words ]]
+ upvars+=("$vwords")
+ upargs+=(-a${#words[@]} $vwords "${words[@]}")
+ ((  4  ))
+ local cur cword prev words
+ _upvars -v cur '' -v cword 1 -v prev ls -a2 words ls ''
+ ((  13  ))
+ ((  13  ))
+ case $1 in
+ [[ -n cur ]]
+ unset -v cur
+ eval 'cur="$3"'
++ cur=
+ shift 3
+ ((  10  ))
+ case $1 in
+ [[ -n cword ]]
+ unset -v cword
+ eval 'cword="$3"'
++ cword=1
+ shift 3
+ ((  7  ))
+ case $1 in
+ [[ -n prev ]]
+ unset -v prev
+ eval 'prev="$3"'
++ prev=ls
+ shift 3
+ ((  4  ))
+ case $1 in
+ [[ -n 2 ]]
+ printf %d 2
+ [[ -n words ]]
+ unset -v words
+ eval 'words=("${@:3:2}")'
++ words=("${@:3:2}")
+ shift 4
+ ((  0  ))
+ _variables
+ [[ '' =~ ^(\$(\{[!#]?)?)([A-Za-z0-9_]*)$ ]]
+ [[ '' =~ ^(\$\{[#!]?)([A-Za-z0-9_]*)\[([^]]*)$ ]]
+ [[ '' =~ ^\$\{[#!]?[A-Za-z0-9_]*\[.*]$ ]]
+ case $prev in
+ return 1
+ [[ '' == @(?([0-9])<|?([0-9&])>?(>)|>&)* ]]
+ [[ ls == @(?([0-9])<|?([0-9&])>?(>)|>&) ]]
+ local i skip
+ (( i=1 ))
+ (( i < 2 ))
+ [[ '' == @(?([0-9])<|?([0-9&])>?(>)|>&)* ]]
+ i=2
+ (( 1 ))
+ (( i < 2 ))
+ [[ 1 -le 0 ]]
+ prev=ls
+ [[ -n false ]]
+ _split_longopt
+ [[ '' == --?*=* ]]
+ return 1
+ return 0
+ case "${prev,,}" in
+ false
+ [[ '' == -* ]]
+ [[ ls == @(rmdir|chroot) ]]
+ [[ ls == mkdir ]]
+ _filedir
+ local 'IFS=
'
+ _tilde ''
+ local result=0
+ [[ '' == \~* ]]
+ return 0
+ local -a toks
+ local x tmp
++ compgen -d -- ''
+ x=
+ [[ '' != -d ]]
+ local quoted
+ _quote_readline_by_ref '' quoted
+ '[' -z '' ']'
+ printf -v quoted %s ''
+ [[ '' == *\\* ]]
+ [[ '' == \$* ]]
+ local xspec=
++ compgen -f -X '' --
+ x=
+ [[ -n '' ]]
+ [[ 0 -ne 0 ]]

Here's my pc information.

$ uname -a
Linux seongwoo 5.4.0-72-generic #80~18.04.1-Ubuntu SMP Mon Apr 12 23:26:25 UTC 2021 x86_64 x86_64 x86_64 GNU/Linux

Although I'm using oh-my-zsh, it has same trouble when I exec /bin/bash.