diff --git a/pytential/qbx/fmm.py b/pytential/qbx/fmm.py
index 994c8ff78317bf75f510591645e5411bf9601a14..46d7ae880384f7dfbe44c21b7aea836ffdd4f6d3 100644
--- a/pytential/qbx/fmm.py
+++ b/pytential/qbx/fmm.py
@@ -809,7 +809,8 @@ def assemble_performance_data(geo_data, uses_pde_expansions,
 
     # {{{ evaluate locals
 
-    result["eval_part"] = tree.ntargets * ncoeffs_fmm
+    non_qbx_box_targets = geo_data.non_qbx_box_target_lists()
+    result["eval_part"] = non_qbx_box_targets.nfiltered_targets * ncoeffs_fmm
 
     # }}}