[SDPhantom]

I was bored, here's some code.

local CachedText={};
local function OnShow(self) CachedText[self]=self:GetText(); end
local function OnTextChanged(self) local txt=self:GetText(); if txt~="" then CachedText[self]=txt; end end
 
local Hooked={};
hooksecurefunc("ChatEdit_ActivateChat",function(editbox)
    if not Hooked[editbox] then
        editbox:HookScript("OnShow",OnShow);
        editbox:HookScript("OnTextChanged",OnTextChanged);
        OnShow(editbox);--  Aready shown by the time this runs
 
        Hooked[editbox]=true;
    end
end);
 
local Count,Start=0,GetTime();
hooksecurefunc("ChatEdit_SendText",function(editbox)
    local cmd,now=((CachedText[editbox] or ""):match("^/%S+") or ""):upper(),GetTime();
    if IsSecureCmd(cmd) or hash_SlashCmdList[cmd] or hash_EmoteTokenList[cmd] then
--      Our reset command will run this too
        if Count<0 then Count=0; return; end
        if Count<1 then Start=now; end
 
        Count=Count+1;
        local runtime=now-Start;
        print(("%d commands run in %0.2f seconds. (%0.2f commands per second)"):format(Count,runtime,Count/runtime));
    end
end);
 
function SlashCmdList.SLASHCOUNT_RESET()
--  Our hook will finish the reset
    Count=-1;
end
SLASH_SLASHCOUNT_RESET1="/slashcountreset";
SLASH_SLASHCOUNT_RESET2="/screset";