# UNDF: UNDF-2026-000001049
--- a/src/ikbd.c
+++ b/src/ikbd.c
@@ -218,6 +218,28 @@ static const struct {
   void (*pCallFunction)(void);
 } KeyboardCommands[] =
 {
+	/* Dispatch table built at init from KeyboardCommands[] for O(1) lookup. */
+	/* See IKBD_InitDispatch() and IKBD_RunKeyboardCommand(). */
 	/* Known messages, counts include command byte */
 	{ 0x80,2,  IKBD_Cmd_Reset },
 	{ 0x07,2,  IKBD_Cmd_MouseAction },
@@ -258,6 +280,33 @@ static const struct {
 	{ 0xFF,0,  NULL }  /* Term */
 };

+/* Dispatch table: indexed by command byte, holds index into KeyboardCommands[]
+ * or -1 for unknown commands. Built once by IKBD_InitDispatch(). */
+static int IKBDCmdIndex[256];
+
+/**
+ * Build the O(1) command-dispatch index from KeyboardCommands[].
+ * Called once during IKBD initialisation.
+ */
+static void IKBD_InitDispatch(void)
+{
+	int i;
+	for (i = 0; i < 256; i++)
+		IKBDCmdIndex[i] = -1;
+	for (i = 0; KeyboardCommands[i].Command != 0xFF; i++)
+		IKBDCmdIndex[KeyboardCommands[i].Command] = i;
+}
+

 /*----------------------------------------------------------------------*/
 /* Variables/defines/functions used to transfer data between the	*/
@@ -830,6 +879,7 @@ void IKBD_Reset(bool bCold)
 	/* Reset */
 	memset(&Keyboard, 0, sizeof(Keyboard));

+	IKBD_InitDispatch();
+
 	/* IKBD gets reset whenever the computer does */
 	IKBD_ResetKeyboardProcessor();

@@ -1854,22 +1904,22 @@ static void IKBD_RunKeyboardCommand(uint8_t aciabyte)
 {
-	int i=0;

 	/* Write into our keyboard input buffer if it's not full yet */
 	if ( Keyboard.nBytesInInputBuffer < SIZE_KEYBOARDINPUT_BUFFER )
 		Keyboard.InputBuffer[Keyboard.nBytesInInputBuffer++] = aciabyte;

-	/* Now check bytes to see if we have a valid/in-valid command string set */
-	while (KeyboardCommands[i].Command!=0xff)
-	{
-		/* Found command? */
-		if (KeyboardCommands[i].Command==Keyboard.InputBuffer[0])
-		{
-			/* If the command is complete (with its possible parameters) we can execute it */
-			/* Else, we wait for the next bytes until the command is complete */
-			if (KeyboardCommands[i].NumParameters==Keyboard.nBytesInInputBuffer)
-			{
-				/* Any new valid command will unpause the output (if command 0x13 was used) */
-				Keyboard.PauseOutput = false;
-
-				CALL_VAR(KeyboardCommands[i].pCallFunction);
-				Keyboard.nBytesInInputBuffer = 0;	/* Clear input buffer after processing a command */
-			}
-
-			return;
-		}
-
-		i++;
-	}
-
-	/* Command not known, reset buffer(IKBD assumes a NOP) */
-	Keyboard.nBytesInInputBuffer = 0;
+	/* O(1) dispatch: look up command byte directly, no linear scan needed. */
+	{
+		int idx = IKBDCmdIndex[(unsigned char)Keyboard.InputBuffer[0]];
+		if (idx >= 0)
+		{
+			/* If the command is complete (with its possible parameters) we can execute it */
+			/* Else, we wait for the next bytes until the command is complete */
+			if (KeyboardCommands[idx].NumParameters==Keyboard.nBytesInInputBuffer)
+			{
+				/* Any new valid command will unpause the output (if command 0x13 was used) */
+				Keyboard.PauseOutput = false;
+
+				CALL_VAR(KeyboardCommands[idx].pCallFunction);
+				Keyboard.nBytesInInputBuffer = 0;	/* Clear input buffer after processing a command */
+			}
+
+			return;
+		}
+
+		/* Command not known, reset buffer (IKBD assumes a NOP) */
+		Keyboard.nBytesInInputBuffer = 0;
+	}
 }