Index: ChangeLog
==================================================================
--- ChangeLog
+++ ChangeLog
@@ -1,5 +1,10 @@
+2025-04-16  Sergei Golovan  <sgolovan@nes.ru>
+
+	* chats.tcl, plugins/chat/nick_colors.tcl: Cache the groupchat roster
+	  and not rebuild it every time it needs to be redrawn.
+
 2025-04-13  Sergei Golovan  <sgolovan@nes.ru>
 
 	* plugins/unix/tktray.tcl: Add a workaround for a race condition in
 	  Tcl 9 when the configure events for size of the tray icon come in
 	  incorrect order.

Index: chats.tcl
==================================================================
--- chats.tcl
+++ chats.tcl
@@ -442,10 +442,20 @@
     hook::run open_chat_pre_hook $chatid $type
 
     set chats(type,$chatid) $type
     set chats(subject,$chatid) ""
     set chats(exit_status,$chatid) ""
+
+    if {$type eq "groupchat"} {
+        # Variable to hold groupchat roster items
+
+        set chats(roster,$chatid) [dict create moderator {} \
+                                               participant {} \
+                                               visitor {} \
+                                               user {}]
+    }
+
     add_to_opened $chatid
 
     set chat_id($cw) $chatid
 
     lassign [chat::window_titles $chatid] chats(tabtitlename,$chatid) \
@@ -1108,84 +1118,114 @@
 hook::add client_presence_hook chat::change_presence 70
 
 ###############################################################################
 
 proc chat::process_roster_event {chatid jid nick status args} {
-    debugmsg chat "ROSTER: $chatid $jid $nick $status"
+    variable chats
 
-    if {[string equal $nick ""]} return
+    debugmsg chat "ROSTER: $chatid $jid $nick $status $args"
+
+    if {$nick eq ""} return
+
+    foreach role {moderator participant visitor user} {
+        dict unset chats(roster,$chatid) $role $nick
+    }
+
+    if {$status ne "unavailable"} {
+        set role user
+        array set tmp $args
+        switch -- $tmp(-role) {
+            moderator -
+            participant -
+            visitor {
+                set role $tmp(-role)
+            }
+            default {
+                set role user
+            }
+        }
+
+        if {$::plugins::nickcolors::options(use_colored_roster_nicks)} {
+            set foreground [plugins::nickcolors::get_color $nick]
+        } else {
+            set foreground [ifacetk::roster::get_foreground $status]
+        }
+
+        dict set chats(roster,$chatid) $role $nick [list $jid $status $foreground]
+    }
+
+    chat::redraw_roster_after_idle $chatid
+}
+
+proc chat::update_roster_foregrounds {chatid} {
+    variable chats
+
+    foreach role {moderator participant visitor user} {
+        dict for {nick val} [dict get $chats(roster,$chatid) $role] {
+            lassign $val jid status foreground
+
+            if {$::plugins::nickcolors::options(use_colored_roster_nicks)} {
+                set foreground [plugins::nickcolors::get_color $nick]
+            } else {
+                set foreground [ifacetk::roster::get_foreground $status]
+            }
+
+            dict set chats(roster,$chatid) $role $nick [list $jid $status $foreground]
+        }
+    }
 
     chat::redraw_roster_after_idle $chatid
 }
 
 namespace eval chat {
     variable g2l
-    array set g2l [list 1 [::msgcat::mc "Moderators"] \
-                        2 [::msgcat::mc "Participants"] \
-                        3 [::msgcat::mc "Visitors"] \
-                        4 [::msgcat::mc "Users"]]
+    array set g2l [list moderator   [::msgcat::mc "Moderators"] \
+                        participant [::msgcat::mc "Participants"] \
+                        visitor     [::msgcat::mc "Visitors"] \
+                        user        [::msgcat::mc "Users"]]
 }
 
 proc chat::redraw_roster {chatid} {
     variable g2l
+    variable chats
 
     set userswin [users_win $chatid]
 
     if {![winfo exists $userswin]} return
 
     ifacetk::roster::clear $userswin 0
 
     set xlib [get_xlib $chatid]
-    set group [get_jid $chatid]
-
-    set levels {}
-    foreach nick [::muc::roster $chatid] {
-        set jid $group/$nick
-        set role [::muc::get_role $xlib $jid]
-
-        switch -- $role {
-            moderator   {set level 1}
-            participant {set level 2}
-            visitor     {set level 3}
-            default     {set level 4}
-        }
-        lappend levels $level
-        lappend levelusers($level) [list $jid $nick]
-    }
-    set levels [lsort -unique $levels]
-
-    foreach level $levels {
-        ifacetk::roster::addline $userswin group \
-            "$g2l($level) ([llength $levelusers($level)])" $level $level {} 0
-
-        foreach item [lsort -index 1 -dictionary $levelusers($level)] {
-            lassign $item jid nick
-            set status [get_user_status $xlib $jid]
-
-            if {$::plugins::nickcolors::options(use_colored_roster_nicks)} {
-                set foreground [plugins::nickcolors::get_color $nick]
-            } else {
-                set foreground [ifacetk::roster::get_foreground $status]
-            }
-            ifacetk::roster::addline $userswin jid $nick \
-                [list $xlib $jid] $level {} 0 \
-                {} roster/user/$status $foreground
+
+    foreach role {moderator participant visitor user} {
+        set users [lsort -dictionary [dict keys [dict get $chats(roster,$chatid) $role]]]
+        set nusers [llength $users]
+        if {$nusers == 0} {
+            continue
+        }
+        ifacetk::roster::addline $userswin group "$g2l($role) ($nusers)" $role $role {} 0
+
+        foreach nick $users {
+            lassign [dict get $chats(roster,$chatid) $role $nick] jid status foreground
+
+            ifacetk::roster::addline $userswin jid $nick [list $xlib $jid] $role {} 0 \
+                                     {} roster/user/$status $foreground
         }
     }
 
     ifacetk::roster::update_scrollregion $userswin
 }
 
-proc chat::redraw_roster_after_idle {group} {
+proc chat::redraw_roster_after_idle {chatid} {
     variable afterid
 
-    if {[info exists afterid($group)]} \
+    if {[info exists afterid($chatid)]} \
         return
 
-    set afterid($group) [after idle "
-        chat::redraw_roster [list $group]
-        unset [list ::chat::afterid($group)]
+    set afterid($chatid) [after idle "
+        chat::redraw_roster [list $chatid]
+        unset [list ::chat::afterid($chatid)]
     "]
 }
 
 proc chat::restore_subject {chatid} {
     variable chats

Index: plugins/chat/nick_colors.tcl
==================================================================
--- plugins/chat/nick_colors.tcl
+++ plugins/chat/nick_colors.tcl
@@ -261,11 +261,11 @@
 
     foreach chatid [chat::opened] {
         set wn [chat::chat_win $chatid]
         if {[winfo exists $wn]} {
             if {[chat::is_groupchat $chatid]} {
-                chat::redraw_roster_after_idle $chatid
+                chat::update_roster_foregrounds $chatid
             }
             foreach nick $NicksInChat($chatid) {
                 set clr [get_color $nick]
                 $wn tag configure NICK-$nick \
                     -foreground [expr {$options(use_colored_nicks) ? $clr : ""}]