diff --git a/pyscf/tdscf/_lr_eig.py b/pyscf/tdscf/_lr_eig.py
index e9a3b6656..328c17319 100644
--- a/pyscf/tdscf/_lr_eig.py
+++ b/pyscf/tdscf/_lr_eig.py
@@ -81,8 +81,9 @@ def eigh(aop, x0, precond, tol_residual=1e-5, lindep=1e-12, nroots=1,
     if MAX_SPACE_INC is None:
         space_inc = nroots
     else:
-        # Adding too many trial bases in each iteration may cause larger errors
-        space_inc = max(nroots, min(MAX_SPACE_INC, x0_size//2))
+        # Keep TD response expansion focused on requested roots instead of
+        # spending residual/preconditioner work on non-target Ritz vectors.
+        space_inc = nroots
 
     max_space = int(max_memory*1e6/8/x0_size / 2 - nroots - space_inc)
     if max_space < nroots * 4 < x0_size: