diff --git a/loopy/check.py b/loopy/check.py
index 266aa72013a2cfbd0e50f880924f1d0bdcb15bc6..3401f7b8d86eb8e89d0bdb0629b5e85d57fff771 100644
--- a/loopy/check.py
+++ b/loopy/check.py
@@ -450,11 +450,27 @@ def check_implemented_domains(kernel, implemented_domains, code=None):
 
     from islpy import align_two
 
+    last_idomains = None
+    last_insn_inames = None
+
     for insn_id, idomains in six.iteritems(implemented_domains):
         insn = kernel.id_to_insn[insn_id]
 
         assert idomains
 
+        insn_inames = kernel.insn_inames(insn)
+
+        # {{{ if we've checked the same thing before, no need to check it again
+
+        if last_idomains is not None and last_insn_inames is not None:
+            if idomains == last_idomains and insn_inames == last_insn_inames:
+                continue
+
+        last_idomains = idomains
+        last_insn_inames = insn_inames
+
+        # }}}
+
         insn_impl_domain = idomains[0]
         for idomain in idomains[1:]:
             insn_impl_domain = insn_impl_domain | idomain
@@ -463,13 +479,12 @@ def check_implemented_domains(kernel, implemented_domains, code=None):
                 assumption_non_param, insn_impl_domain)
         insn_impl_domain = (
                 (insn_impl_domain & assumptions)
-                .project_out_except(kernel.insn_inames(insn), [dim_type.set]))
+                .project_out_except(insn_inames, [dim_type.set]))
 
-        insn_inames = kernel.insn_inames(insn)
         insn_domain = kernel.get_inames_domain(insn_inames)
         assumptions, insn_domain = align_two(assumption_non_param, insn_domain)
         desired_domain = ((insn_domain & assumptions)
-            .project_out_except(kernel.insn_inames(insn), [dim_type.set]))
+            .project_out_except(insn_inames, [dim_type.set]))
 
         insn_impl_domain, desired_domain = align_two(
                 insn_impl_domain, desired_domain)