diff --git a/Changes b/Changes
index a3badf96a..db6a674f5 100644
--- a/Changes
+++ b/Changes
@@ -26,6 +26,7 @@ Verilator 5.033 devel
 * Improve VPI write errors (#5712). [Andrew Nolte]
 * Improve `resetall support (#5728) (#5730). [Ethan Sifferman]
 * Optimize labels as final `if` block statements (#5744).
+* Optimize empty function definition bodies (#5750).
 * Fix error message when call task as a function (#3089). [Matthew Ballance]
 * Fix VPI iteration over hierarchy (#5314) (#5731). [Natan Kreimer]
 * Fix constrained random for > 64-bit associative arrays (#5670) (#5682). [Yilou Wang]
diff --git a/src/V3AstNodeOther.h b/src/V3AstNodeOther.h
index e8b8c425f..91a1ab405 100644
--- a/src/V3AstNodeOther.h
+++ b/src/V3AstNodeOther.h
@@ -625,6 +625,7 @@ class AstCFunc final : public AstNode {
     bool m_isTrace : 1;  // Function is related to tracing
     bool m_dontCombine : 1;  // V3Combine shouldn't compare this func tree, it's special
     bool m_declPrivate : 1;  // Declare it private
+    bool m_keepIfEmpty : 1;  // Keep declaration and definition separate, even if empty
     bool m_slow : 1;  // Slow routine, called once or just at init time
     bool m_funcPublic : 1;  // From user public task/function
     bool m_isConstructor : 1;  // Is C class constructor
@@ -655,6 +656,7 @@ public:
         m_isTrace = false;
         m_dontCombine = false;
         m_declPrivate = false;
+        m_keepIfEmpty = false;
         m_slow = false;
         m_funcPublic = false;
         m_isConstructor = false;
@@ -706,6 +708,8 @@ public:
     bool dontInline() const { return dontCombine() || slow() || funcPublic(); }
     bool declPrivate() const { return m_declPrivate; }
     void declPrivate(bool flag) { m_declPrivate = flag; }
+    bool keepIfEmpty() const VL_MT_SAFE { return m_keepIfEmpty; }
+    void keepIfEmpty(bool flag) { m_keepIfEmpty = flag; }
     bool slow() const VL_MT_SAFE { return m_slow; }
     void slow(bool flag) { m_slow = flag; }
     bool funcPublic() const { return m_funcPublic; }
@@ -749,8 +753,7 @@ public:
     void cost(int cost) { m_cost = cost; }
     // Special methods
     bool emptyBody() const {
-        return argsp() == nullptr && initsp() == nullptr && stmtsp() == nullptr
-               && finalsp() == nullptr;
+        return !keepIfEmpty() && !argsp() && !initsp() && !stmtsp() && !finalsp();
     }
 };
 class AstCLocalScope final : public AstNode {
diff --git a/src/V3AstNodes.cpp b/src/V3AstNodes.cpp
index f8b4a6f9b..ab9c98fe0 100644
--- a/src/V3AstNodes.cpp
+++ b/src/V3AstNodes.cpp
@@ -2865,15 +2865,17 @@ void AstCFile::dumpJson(std::ostream& str) const {
 void AstCFunc::dump(std::ostream& str) const {
     this->AstNode::dump(str);
     if (slow()) str << " [SLOW]";
-    if (dpiPure()) str << " [DPIPURE]";
     if (isStatic()) str << " [STATIC]";
+    if (dpiContext()) str << " [DPICTX]";
     if (dpiExportDispatcher()) str << " [DPIED]";
     if (dpiExportImpl()) str << " [DPIEI]";
     if (dpiImportPrototype()) str << " [DPIIP]";
     if (dpiImportWrapper()) str << " [DPIIW]";
-    if (dpiContext()) str << " [DPICTX]";
+    if (dpiPure()) str << " [DPIPURE]";
     if (isConstructor()) str << " [CTOR]";
     if (isDestructor()) str << " [DTOR]";
+    if (isMethod()) str << " [METHOD]";
+    if (isLoose()) str << " [LOOSE]";
     if (isVirtual()) str << " [VIRT]";
     if (isCoroutine()) str << " [CORO]";
     if (needProcess()) str << " [NPRC]";
diff --git a/src/V3CCtors.cpp b/src/V3CCtors.cpp
index 045628e6a..30b5d5f69 100644
--- a/src/V3CCtors.cpp
+++ b/src/V3CCtors.cpp
@@ -62,6 +62,7 @@ class V3CCtorsBuilder final {
         AstCFunc* const funcp = new AstCFunc{m_modp->fileline(), funcName, nullptr, "void"};
         funcp->isStatic(false);
         funcp->isLoose(!m_type.isClass());
+        funcp->keepIfEmpty(true);  // TODO relax
         funcp->declPrivate(true);
         funcp->slow(!m_type.isClass());  // Only classes construct on fast path
         string preventUnusedStmt;
@@ -210,6 +211,7 @@ void V3CCtors::evalAsserts() {
     funcp->declPrivate(true);
     funcp->isStatic(false);
     funcp->isLoose(true);
+    funcp->keepIfEmpty(true);
     funcp->slow(false);
     funcp->ifdef("VL_DEBUG");
     modp->addStmtsp(funcp);
diff --git a/src/V3EmitCBase.cpp b/src/V3EmitCBase.cpp
index 547a17884..2cb45c20b 100644
--- a/src/V3EmitCBase.cpp
+++ b/src/V3EmitCBase.cpp
@@ -171,7 +171,11 @@ void EmitCBaseVisitorConst::emitCFuncDecl(const AstCFunc* funcp, const AstNodeMo
         putns(funcp, "virtual ");
     }
     emitCFuncHeader(funcp, modp, /* withScope: */ false);
-    putns(funcp, ";\n");
+    if (funcp->emptyBody() && !funcp->isLoose() && !cLinkage) {
+        putns(funcp, " {}\n");
+    } else {
+        putns(funcp, ";\n");
+    }
     if (!funcp->ifdef().empty()) putns(funcp, "#endif  // " + funcp->ifdef() + "\n");
 }
 
diff --git a/src/V3EmitCFunc.h b/src/V3EmitCFunc.h
index 972970647..00374ae1f 100644
--- a/src/V3EmitCFunc.h
+++ b/src/V3EmitCFunc.h
@@ -280,6 +280,7 @@ public:
     // VISITORS
     using EmitCConstInit::visit;
     void visit(AstCFunc* nodep) override {
+        if (nodep->emptyBody() && !nodep->isLoose()) return;
         VL_RESTORER(m_useSelfForThis);
         VL_RESTORER(m_cfuncp);
         VL_RESTORER(m_instantiatesOwnProcess)
diff --git a/src/V3Sched.cpp b/src/V3Sched.cpp
index 61a7f21d1..76f6cfbdc 100644
--- a/src/V3Sched.cpp
+++ b/src/V3Sched.cpp
@@ -70,6 +70,7 @@ AstCFunc* makeSubFunction(AstNetlist* netlistp, const string& name, bool slow) {
 AstCFunc* makeTopFunction(AstNetlist* netlistp, const string& name, bool slow) {
     AstCFunc* const funcp = makeSubFunction(netlistp, name, slow);
     funcp->entryPoint(true);
+    funcp->keepIfEmpty(true);
     return funcp;
 }
 
diff --git a/test_regress/t/t_timing_debug2.out b/test_regress/t/t_timing_debug2.out
index ac4dd1943..a00833c4e 100644
--- a/test_regress/t/t_timing_debug2.out
+++ b/test_regress/t/t_timing_debug2.out
@@ -185,7 +185,6 @@
 -V{t#,#}             Awaiting time 101: Process waiting at t/t_timing_class.v:274
 -V{t#,#}         Resuming delayed processes
 -V{t#,#}             Resuming: Process waiting at t/t_timing_class.v:173
--V{t#,#}+        Vt_timing_debug2_t__03a__03aDelay10::__VnoInFunc_do_sth_else
 -V{t#,#}+        Vt_timing_debug2_t__03a__03aDelay20::__VnoInFunc_do_delay
 -V{t#,#}             Resuming: Process waiting at t/t_timing_class.v:247
 -V{t#,#}             Process forked at t/t_timing_class.v:246 finished
@@ -499,7 +498,6 @@
 -V{t#,#}             Resuming: Process waiting at t/t_timing_class.v:257
 -V{t#,#}+        Vt_timing_debug2_t__03a__03aForkDelayClass::__VnoInFunc_do_delay
 -V{t#,#}             Resuming: Process waiting at t/t_timing_class.v:174
--V{t#,#}+        Vt_timing_debug2_t__03a__03aDelay20::__VnoInFunc_do_sth_else
 -V{t#,#}+        Vt_timing_debug2_t__03a__03aDelay40::__VnoInFunc_do_delay
 -V{t#,#}             Resuming: Process waiting at t/t_timing_class.v:131
 -V{t#,#}+        Vt_timing_debug2_t__03a__03aClkClass::__VnoInFunc_flip
@@ -1038,9 +1036,7 @@
 -V{t#,#}             Process forked at t/t_timing_class.v:250 finished
 -V{t#,#}             Resuming: Process waiting at t/t_timing_class.v:245
 -V{t#,#}             Resuming: Process waiting at t/t_timing_class.v:175
--V{t#,#}+        Vt_timing_debug2_t__03a__03aDelay40::__VnoInFunc_do_sth_else
 -V{t#,#}+        Vt_timing_debug2_t__03a__03aNoDelay::__VnoInFunc_do_delay
--V{t#,#}+        Vt_timing_debug2_t__03a__03aNoDelay::__VnoInFunc_do_sth_else
 -V{t#,#}+      Vt_timing_debug2_t___eval_initial__TOP__t__Vtiming__6____Vfork_1__0
 -V{t#,#}+        Vt_timing_debug2_t__03a__03aAssignDelayClass::__VnoInFunc_do_assign
 -V{t#,#}             Resuming: Process waiting at t/t_timing_class.v:76
@@ -1082,8 +1078,6 @@
 -V{t#,#}End-of-eval cleanup
 -V{t#,#}+++++TOP Evaluate Vt_timing_debug2::eval_step
 -V{t#,#}+    Vt_timing_debug2___024root___eval_debug_assertions
--V{t#,#}+        Vt_timing_debug2_t__03a__03aForkDelayClass::~
--V{t#,#}+        Vt_timing_debug2_t__03a__03aForkClass::~
 -V{t#,#}+ Eval
 -V{t#,#}+    Vt_timing_debug2___024root___eval
 -V{t#,#}+    Vt_timing_debug2___024root___eval_phase__act
@@ -1236,7 +1230,6 @@
 -V{t#,#}End-of-eval cleanup
 -V{t#,#}+++++TOP Evaluate Vt_timing_debug2::eval_step
 -V{t#,#}+    Vt_timing_debug2___024root___eval_debug_assertions
--V{t#,#}+        Vt_timing_debug2_t__03a__03aAssignDelayClass::~
 -V{t#,#}+ Eval
 -V{t#,#}+    Vt_timing_debug2___024root___eval
 -V{t#,#}+    Vt_timing_debug2___024root___eval_phase__act
@@ -1308,18 +1301,3 @@
 -V{t#,#}+    Vt_timing_debug2___024root___eval_phase__nba
 -V{t#,#}End-of-eval cleanup
 -V{t#,#}+    Vt_timing_debug2___024root___eval_final
--V{t#,#}+        Vt_timing_debug2_t__03a__03aDelay40::~
--V{t#,#}+        Vt_timing_debug2_t__03a__03aDelayClass::~
--V{t#,#}+        Vt_timing_debug2_t__03a__03aDelay20::~
--V{t#,#}+        Vt_timing_debug2_t__03a__03aDelayClass::~
--V{t#,#}+        Vt_timing_debug2_t__03a__03aDelay10::~
--V{t#,#}+        Vt_timing_debug2_t__03a__03aDelayClass::~
--V{t#,#}+        Vt_timing_debug2_t__03a__03aNoDelay::~
--V{t#,#}+        Vt_timing_debug2_t__03a__03aDelayClass::~
--V{t#,#}+        Vt_timing_debug2_t__03a__03aClkClass::~
--V{t#,#}+        Vt_timing_debug2_t__03a__03aLocalWaitClass::~
--V{t#,#}+          Vt_timing_debug2___024unit__03a__03aBaseClass::~
--V{t#,#}+        Vt_timing_debug2_t__03a__03aWaitClass::~
--V{t#,#}+          Vt_timing_debug2___024unit__03a__03aBaseClass::~
--V{t#,#}+        Vt_timing_debug2_t__03a__03aEventClass::~
--V{t#,#}+          Vt_timing_debug2___024unit__03a__03aBaseClass::~