diff --git a/src/gallium/drivers/radeonsi/si_state_shaders.cpp b/src/gallium/drivers/radeonsi/si_state_shaders.cpp
index 72527ec63b5..add5b8bb498 100644
--- a/src/gallium/drivers/radeonsi/si_state_shaders.cpp
+++ b/src/gallium/drivers/radeonsi/si_state_shaders.cpp
@@ -1521,6 +1521,7 @@ static void gfx10_shader_ngg(struct si_screen *sscreen, struct si_shader *shader
       shader->ge_cntl = S_03096C_PRIMS_PER_SUBGRP(shader->ngg.max_gsprims) |
                         S_03096C_VERTS_PER_SUBGRP(shader->ngg.hw_max_esverts) |
                         S_03096C_BREAK_PRIMGRP_AT_EOI(break_wave_at_eoi) |
+                        /* This should be <= 252 for performance. 256 works too but is slower. */
                         S_03096C_PRIM_GRP_SIZE_GFX11(
                            CLAMP(252 / MAX2(shader->ngg.prim_amp_factor, 1),
                                  1, 256));