diff --git a/src/ast/rewriter/var_subst.cpp b/src/ast/rewriter/var_subst.cpp
index ec33bd2650..532a49ec5f 100644
--- a/src/ast/rewriter/var_subst.cpp
+++ b/src/ast/rewriter/var_subst.cpp
@@ -52,6 +52,20 @@ expr_ref var_subst::operator()(expr * n, unsigned num_args, expr * const * args)
         rep(n, result);
         return result;
     }
+    if (is_app(n) && all_of(*to_app(n), [&](expr* arg) { return is_ground(arg) || is_var(arg); })) {
+        ptr_buffer<expr> new_args;
+        for (auto arg : *to_app(n)) {
+            if (is_ground(arg))
+                new_args.push_back(arg);
+            else {
+                unsigned idx = to_var(arg)->get_idx();
+                new_args.push_back(m_std_order ? args[idx] : args[num_args - idx - 1]);
+            }
+        }
+        result = m.mk_app(to_app(n)->get_decl(), new_args.size(), new_args.data());
+        //        verbose_stream() << result << "\n";
+        return result;
+    }
     SASSERT(is_well_sorted(result.m(), n));
     m_reducer.reset();
     if (m_std_order)
diff --git a/src/cmd_context/cmd_context.cpp b/src/cmd_context/cmd_context.cpp
index 5f5195bb9d..ca9bbec268 100644
--- a/src/cmd_context/cmd_context.cpp
+++ b/src/cmd_context/cmd_context.cpp
@@ -33,7 +33,6 @@ Module Name:
 #include "ast/fpa_decl_plugin.h"
 #include "ast/special_relations_decl_plugin.h"
 #include "ast/ast_pp.h"
-#include "ast/rewriter/var_subst.h"
 #include "ast/pp.h"
 #include "ast/ast_smt2_pp.h"
 #include "ast/ast_ll_pp.h"
@@ -406,8 +405,7 @@ void cmd_context::insert_macro(symbol const& s, unsigned arity, sort*const* doma
     recfun::promise_def d = p.ensure_def(s, arity, domain, t->get_sort(), false);
 
     // recursive functions have opposite calling convention from macros!
-    var_subst sub(m(), true);
-    expr_ref tt = sub(t, rvars);
+    expr_ref tt = std_subst()(t, rvars);
     p.set_definition(replace, d, true, vars.size(), vars.data(), tt);
     register_fun(s, d.get_def()->get_decl());
 }
@@ -461,7 +459,6 @@ bool cmd_context::macros_find(symbol const& s, unsigned n, expr*const* args, exp
         if (eq) {
             t = d.m_body;
             t = sub(t);
-            verbose_stream() << "macro " << t << "\n";
             ptr_buffer<sort> domain;
             for (unsigned i = 0; i < n; ++i)
                 domain.push_back(args[i]->get_sort());
@@ -1257,9 +1254,8 @@ bool cmd_context::try_mk_macro_app(symbol const & s, unsigned num_args, expr * c
               tout << "s: " << s << "\n";
               tout << "body:\n" << mk_ismt2_pp(_t, m()) << "\n";
               tout << "args:\n"; for (unsigned i = 0; i < num_args; i++) tout << mk_ismt2_pp(args[i], m()) << "\n" << mk_pp(args[i]->get_sort(), m()) << "\n";);
-        var_subst subst(m(), false);
         scoped_rlimit no_limit(m().limit(), 0);
-        result = subst(_t, coerced_args);
+        result = rev_subst()(_t, coerced_args);
         if (well_sorted_check_enabled() && !is_well_sorted(m(), result))
             throw cmd_exception("invalid macro application, sort mismatch ", s);
         return true;
@@ -1524,6 +1520,8 @@ void cmd_context::reset(bool finalize) {
         if (m_own_manager) {
             dealloc(m_manager);
             m_manager = nullptr;
+            m_std_subst = nullptr;
+            m_rev_subst = nullptr;
             m_manager_initialized = false;
         }
         else {
diff --git a/src/cmd_context/cmd_context.h b/src/cmd_context/cmd_context.h
index cd43203a7f..dde1d7962e 100644
--- a/src/cmd_context/cmd_context.h
+++ b/src/cmd_context/cmd_context.h
@@ -33,6 +33,7 @@ Module Name:
 #include "ast/datatype_decl_plugin.h"
 #include "ast/recfun_decl_plugin.h"
 #include "ast/rewriter/seq_rewriter.h"
+#include "ast/rewriter/var_subst.h"
 #include "ast/converters/generic_model_converter.h"
 #include "solver/solver.h"
 #include "solver/check_logic.h"
@@ -280,6 +281,7 @@ class cmd_context : public progress_callback, public tactic_manager, public ast_
     ptr_vector<expr>             m_assertions;
     std::vector<std::string>     m_assertion_strings;
     ptr_vector<expr>             m_assertion_names; // named assertions are represented using boolean variables.
+    scoped_ptr<var_subst>        m_std_subst, m_rev_subst;
 
     struct scope {
         unsigned m_func_decls_stack_lim;
@@ -317,6 +319,9 @@ class cmd_context : public progress_callback, public tactic_manager, public ast_
     scoped_ptr<pp_env>            m_pp_env;
     pp_env & get_pp_env() const;
 
+    var_subst& std_subst() { if (!m_std_subst) m_std_subst = alloc(var_subst, m(), true); return *m_std_subst; }
+    var_subst& rev_subst() { if (!m_rev_subst) m_rev_subst = alloc(var_subst, m(), false); return *m_rev_subst; }
+
     void register_builtin_sorts(decl_plugin * p);
     void register_builtin_ops(decl_plugin * p);
     void load_plugin(symbol const & name, bool install_names, svector<family_id>& fids);