perf(git): minor performance cleanups

lua/git/cmd.lua

@@ -18,16 +18,8 @@ local SPLIT_HANDLERS = {
 ---@type string[]?
 local cached_cmds
 
----@return string[]
-local function git_cmds()
-    if cached_cmds then
-        return cached_cmds
-    end
-    local result = vim.system(
-        { "git", "--list-cmds=main,others,alias" },
-        { text = true }
-    )
-        :wait()
+---@param result vim.SystemCompleted
+local function populate_cached_cmds(result)
     cached_cmds = {}
     if result.code == 0 then
         for line in (result.stdout or ""):gmatch("[^\r\n]+") do
@@ -37,7 +29,31 @@ local function git_cmds()
         end
         table.sort(cached_cmds)
     end
-    return cached_cmds
+end
+
+---Prime `cached_cmds` asynchronously so the first `:G <Tab>` doesn't block.
+local function prefetch_cmds()
+    vim.system(
+        { "git", "--list-cmds=main,others,alias" },
+        { text = true },
+        function(result)
+            vim.schedule(function()
+                populate_cached_cmds(result)
+            end)
+        end
+    )
+end
+
+---@return string[]
+local function git_cmds()
+    if cached_cmds then
+        return cached_cmds
+    end
+    populate_cached_cmds(
+        vim.system({ "git", "--list-cmds=main,others,alias" }, { text = true })
+            :wait()
+    )
+    return cached_cmds or {}
 end
 
 ---@param content string
@@ -204,6 +220,7 @@ local function complete(arg_lead, cmd_line, _)
 end
 
 function M.setup()
+    prefetch_cmds()
     vim.api.nvim_create_user_command("G", function(opts)
         M.run(opts.fargs)
     end, {