diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index e35eaff5..fab0e93a 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -13,8 +13,8 @@ env:
   CTEST_OUTPUT_ON_FAILURE: "ON"
   DEBIAN_FRONTEND: noninteractive
   UPX_CMAKE_BUILD_FLAGS: --verbose
-  # 2023-10-23
-  ZIG_DIST_VERSION: 0.12.0-dev.1200+5f92b070b
+  # 2023-10-24
+  ZIG_DIST_VERSION: 0.12.0-dev.1245+a07f288eb
 
 jobs:
   job-rebuild-and-verify-stubs:
diff --git a/.github/workflows/weekly-ci-cc-zigcc.yml b/.github/workflows/weekly-ci-cc-zigcc.yml
index 07f90b44..eb63d339 100644
--- a/.github/workflows/weekly-ci-cc-zigcc.yml
+++ b/.github/workflows/weekly-ci-cc-zigcc.yml
@@ -11,8 +11,8 @@ env:
   CMAKE_REQUIRED_QUIET: "OFF"
   CTEST_OUTPUT_ON_FAILURE: "ON"
   DEBIAN_FRONTEND: noninteractive
-  # 2023-10-23
-  ZIG_DIST_VERSION: 0.12.0-dev.1200+5f92b070b
+  # 2023-10-24
+  ZIG_DIST_VERSION: 0.12.0-dev.1245+a07f288eb
 
 jobs:
   job-linux-zigcc: # uses cmake + make
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 6d84752d..c1dc6942 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -281,6 +281,30 @@ if(NOT CMAKE_C_COMPILER_ID MATCHES "^MSVC")
     endif()
 endif()
 
+# compile a source file with -O2 even in Debug build
+function(upx_compile_source_debug_with_O2)
+    set(flags "$<$<CONFIG:Debug>:-O2>")
+    if (CMAKE_VERSION VERSION_LESS 3.8)
+        # 3.8: The COMPILE_FLAGS source file property learned to support generator expressions
+        if (is_multi_config OR NOT CMAKE_BUILD_TYPE MATCHES "^Debug$")
+            return()
+        endif()
+        set(flags "-O2")
+    endif()
+    foreach(t ${ARGV})
+        if(MSVC_FRONTEND)
+            # MSVC uses some Debug compilation options like -RTC1 that are incompatible with -O2
+        else()
+            get_source_file_property(prop ${t} COMPILE_FLAGS)
+            if(prop MATCHES "^(NOTFOUND)?$")
+                set_source_files_properties(${t} PROPERTIES COMPILE_FLAGS "${flags}")
+            else()
+                set_source_files_properties(${t} PROPERTIES COMPILE_FLAGS "${prop} ${flags}")
+            endif()
+        endif()
+    endforeach()
+endfunction()
+
 # compile a target with -O2 even in Debug build
 function(upx_compile_target_debug_with_O2)
     foreach(t ${ARGV})
@@ -456,6 +480,9 @@ if(HAVE_UTIMENSAT)
         target_compile_definitions(${t} PRIVATE HAVE_STRUCT_STAT_ST_MTIMESPEC_TV_NSEC=1)
     endif()
 endif()
+# improve speed of the debug versions
+upx_compile_source_debug_with_O2(src/compress/compress_lzma.cpp)
+upx_compile_source_debug_with_O2(src/filter/filter_impl.cpp)
 #upx_compile_target_debug_with_O2(${t})
 upx_sanitize_target(${t})
 if(MSVC_FRONTEND)
@@ -473,6 +500,7 @@ endif()
 if(NOT UPX_CONFIG_CMAKE_DISABLE_TEST)
 
 include(CTest)
+# TODO later: check CMAKE_CROSSCOMPILING_EMULATOR
 if(NOT CMAKE_CROSSCOMPILING)
     add_test(NAME upx-version COMMAND upx --version)
     add_test(NAME upx-help    COMMAND upx --help)
diff --git a/src/p_w32pe_i386.cpp b/src/p_w32pe_i386.cpp
index 532301a9..10741611 100644
--- a/src/p_w32pe_i386.cpp
+++ b/src/p_w32pe_i386.cpp
@@ -233,9 +233,9 @@ void PackW32PeI386::defineSymbols(unsigned ncsection, unsigned upxsection, unsig
     // linker->dumpSymbols();
 }
 
-void PackW32PeI386::addNewRelocations(Reloc &rel, unsigned base) {
+void PackW32PeI386::addNewRelocations(Reloc &rel, unsigned upxsection) {
     if (use_stub_relocs)
-        rel.add(base + linker->getSymbolOffset("PESOCREL") + 1, 3);
+        rel.add(upxsection + linker->getSymbolOffset("PESOCREL") + 1, 3);
 }
 
 void PackW32PeI386::setOhDataBase(const pe_section_t *osection) { oh.database = osection[2].vaddr; }
diff --git a/src/pefile.cpp b/src/pefile.cpp
index 943d5e6e..43c6203b 100644
--- a/src/pefile.cpp
+++ b/src/pefile.cpp
@@ -454,13 +454,6 @@ void PeFile::Reloc::finish(byte *(&result_ptr), unsigned &result_size) {
 #endif
 }
 
-void PeFile::processRelocs(Reloc *rel) // pass2
-{
-    rel->finish(oxrelocs, soxrelocs);
-    if (opt->win32_pe.strip_relocs)
-        soxrelocs = 0;
-}
-
 void PeFile32::processRelocs() // pass1
 {
     big_relocs = 0;
@@ -483,8 +476,8 @@ void PeFile32::processRelocs() // pass1
             ih.objects = tryremove(IDADDR(PEDIR_BASERELOC), ih.objects);
         }
         mb_orelocs.alloc(1);
+        mb_orelocs.clear();
         orelocs = mb_orelocs; // => orelocs now is a SPAN_S
-        orelocs[0] = 0;       // clear
         sorelocs = 0;
         return;
     }
@@ -567,15 +560,17 @@ void PeFile64::processRelocs() // pass1
 {
     big_relocs = 0;
 
-    const unsigned skip = IDADDR(PEDIR_BASERELOC);
-    const unsigned take = IDSIZE(PEDIR_BASERELOC);
-    Reloc rel(ibuf.subref("bad reloc %#x", skip, take), take);
-    const unsigned *counts = rel.getcounts();
+    const unsigned skip1 = IDADDR(PEDIR_BASERELOC);
+    const unsigned take1 = IDSIZE(PEDIR_BASERELOC);
+    Reloc rel(ibuf.subref("bad reloc %#x", skip1, take1), take1);
+    const unsigned *const counts = rel.getcounts();
     unsigned relocnum = 0;
 
     unsigned ic;
     for (ic = 1; ic < 16; ic++)
         relocnum += counts[ic];
+    for (ic = 0; ic < 16; ic++)
+        NO_printf("reloc counts[%u] %u\n", ic, counts[ic]);
 
     if (opt->win32_pe.strip_relocs || relocnum == 0) {
         if (IDSIZE(PEDIR_BASERELOC)) {
@@ -583,6 +578,7 @@ void PeFile64::processRelocs() // pass1
             ih.objects = tryremove(IDADDR(PEDIR_BASERELOC), ih.objects);
         }
         mb_orelocs.alloc(1);
+        mb_orelocs.clear();
         orelocs = mb_orelocs; // => orelocs now is a SPAN_S
         sorelocs = 0;
         return;
@@ -2226,9 +2222,11 @@ void PeFile::callCompressWithFilters(Filter &ft, int filter_strategy, unsigned i
     compressWithFilters(&ft, 2048, NULL_cconf, filter_strategy, ih_codebase, rvamin, 0, nullptr, 0);
 }
 
-void PeFile::callProcessRelocs(Reloc &rel, unsigned &ic) {
+void PeFile::callProcessStubRelocs(Reloc &rel, unsigned &ic) {
     // WinCE wants relocation data at the beginning of a section
-    PeFile::processRelocs(&rel);
+    rel.finish(oxrelocs, soxrelocs);
+    if (opt->win32_pe.strip_relocs)
+        soxrelocs = 0;
     ODADDR(PEDIR_BASERELOC) = soxrelocs ? ic : 0;
     ODSIZE(PEDIR_BASERELOC) = soxrelocs;
     ic += soxrelocs;
@@ -2456,7 +2454,7 @@ void PeFile::pack0(OutputFile *fo, ht &ih, ht &oh, unsigned subsystem_mask,
     const unsigned ncsection = (s1addr + s1size + oam1) & ~oam1;
     const unsigned upxsection = s1addr + ic + c_len;
 
-    Reloc rel(1024); // new relocations are put here
+    Reloc rel(1024); // new stub relocations are put here
     addNewRelocations(rel, upxsection);
 
     // new PE header
@@ -2497,7 +2495,7 @@ void PeFile::pack0(OutputFile *fo, ht &ih, ht &oh, unsigned subsystem_mask,
     if (!last_section_rsrc_only)
         callProcessResources(res, ic);
     if (rel_at_sections_start)
-        callProcessRelocs(rel, ic);
+        callProcessStubRelocs(rel, ic);
 
     processImports2(ic, getProcessImportParam(upxsection));
     ODADDR(PEDIR_IMPORT) = soimpdlls ? ic : 0;
@@ -2514,7 +2512,7 @@ void PeFile::pack0(OutputFile *fo, ht &ih, ht &oh, unsigned subsystem_mask,
     ic += soexport;
 
     if (!rel_at_sections_start)
-        callProcessRelocs(rel, ic);
+        callProcessStubRelocs(rel, ic);
 
     // when the resource is put alone into section 3
     const unsigned res_start = (ic + oam1) & ~oam1;
diff --git a/src/pefile.h b/src/pefile.h
index f476bc6f..f4a47257 100644
--- a/src/pefile.h
+++ b/src/pefile.h
@@ -59,7 +59,7 @@ protected:
     virtual void defineSymbols(unsigned ncsection, unsigned upxsection, unsigned sizeof_oh,
                                unsigned isize_isplit, unsigned s1addr) = 0;
     virtual void addNewRelocations(Reloc &, unsigned) {}
-    void callProcessRelocs(Reloc &rel, unsigned &ic);
+    void callProcessStubRelocs(Reloc &rel, unsigned &ic);
     void callProcessResources(Resource &res, unsigned &ic);
     virtual unsigned getProcessImportParam(unsigned) { return 0; }
     virtual void setOhDataBase(const pe_section_t *osection) = 0;
@@ -106,7 +106,6 @@ protected:
     upx_uint64_t ilinkerGetAddress(const char *, const char *) const;
 
     virtual void processRelocs() = 0;
-    void processRelocs(Reloc *);
     void rebuildRelocs(SPAN_S(byte) &, unsigned bits, unsigned flags, upx_uint64_t imagebase);
     MemBuffer mb_orelocs;
     SPAN_0(byte) orelocs = nullptr;
diff --git a/src/util/cxxlib.h b/src/util/cxxlib.h
index ba6b77c0..c90cbeb8 100644
--- a/src/util/cxxlib.h
+++ b/src/util/cxxlib.h
@@ -134,11 +134,14 @@ struct TriBool final {
     }
 
     // "Third" can mean many things - depending on usage context, so provide some alternate names:
+#if 0
     // constexpr bool isDefault() const noexcept { return isThird(); } // might be misleading
     constexpr bool isIndeterminate() const noexcept { return isThird(); }
+    constexpr bool isNone() const noexcept { return isThird(); }
     constexpr bool isOther() const noexcept { return isThird(); }
     constexpr bool isUndecided() const noexcept { return isThird(); }
     // constexpr bool isUnset() const noexcept { return isThird(); } // might be misleading
+#endif
 
 private:
     value_type value = False; // the actual value of this type