What can I do to fix occasional lagging of terminal emulator?

My terminal emulators are lagging occasionally. It's not heavy a lag. May be once in 20-30 mins( I think). The terminal becomes unresponsive and all the characters I typed during lag appears suddenly. It's not happening in any other app (even in SMPLAYER during 1080p video playback). The lag occurs even during low memory usage(nearly 1 GB free). I thought there might be a problem in xterm and switched to xfce4-terminal emulator. problem still persisted. Then thought there might be a bug in bash and switched to zsh . still no luck. What's happening ? How can I narrow the down problem? system info : Arch + i3 + compton Update1: I thought my history size(1000) might be causing the problem and changed it to 100. And this doesn't seem to work either. Update2: My ~/.bashrc

#
# ~/.bashrc
#

# If not running interactively, don't do anything
[[ $- != *i* ]] && return

alias ls='ls --color=auto'
alias grep='grep --color=auto'

PS1='\[\033[32m\]\u\[\033[33m\]@\[\033[36m\]\h \[\033[31m\]\W\[\033[33m\]\$\[\033[00m\]'


## my settings
alias vi='vim'
alias vi_i3='vim ~/.config/i3/config'
alias pacs='sudo pacman -S'
alias pacss='pacman -Ss'
alias pacsyu='sudo pacman -Syu'
export TERMINAL='xfce4-terminal'
HISTSIZE=100

Update3: But in zsh I used very simple Prompt string without any color. Still it was lagging.