diff --git i/platform/sdl/knativescreenSDL.cpp w/platform/sdl/knativescreenSDL.cpp
index c4e0149..ac1da96 100644
--- i/platform/sdl/knativescreenSDL.cpp
+++ w/platform/sdl/knativescreenSDL.cpp
@@ -708,6 +708,9 @@ void KNativeScreenSDL::recreateMainWindow() {
         
         visible = false;
 
+        // The browser page owns display scaling and fullscreen. Keep the guest
+        // framebuffer intact even when it is larger than the mobile viewport.
+#ifndef __EMSCRIPTEN__
         SDL_DisplayMode dm;
 
         if (SDL_GetDesktopDisplayMode(0, &dm) != 0) {
@@ -747,6 +750,8 @@ void KNativeScreenSDL::recreateMainWindow() {
             }
         }
 
+#endif
+
         window = SDL_CreateWindow("BoxedWine", SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED, cx, cy, flags);
         if (!window) {
             klog_fmt("SDL_CreateWindow failed: %s", SDL_GetError());
diff --git i/project/emscripten/makefile w/project/emscripten/makefile
index a38b378..cc52329 100644
--- i/project/emscripten/makefile
+++ w/project/emscripten/makefile
@@ -102,9 +102,9 @@ $(OBJS): INCLUDES := -I../../include -I../../lib/simde
 $(SOFT_OBJS): INCLUDES := -I../../lib/softfloat/source/include -I../../lib/softfloat/source -I../../lib/softfloat/source/8086-SSE
 
 CXXFLAGS ?= -std=c++20
-CPPFLAGS ?= -O3 -s USE_SDL=2 -s USE_ZLIB=1 -DBOXEDWINE_ZLIB -DSDL2=1 -DBOXEDWINE_DISABLE_UI -DSIMDE_SSE2_NO_NATIVE $(GCC_EXTRA_FLAGS) -Wall -Wno-deprecated-pragma -Wno-format-security -Wno-unused-private-field -Wno-invalid-offsetof -Wno-delete-incomplete -Wno-unused-result -Wno-unknown-pragmas -Wno-unused-local-typedefs -Wno-unused-variable -Wno-unused-function -Wno-unused-but-set-variable $(INCLUDES) $(EXTRA_CPP_FLAGS)
+CPPFLAGS ?= -O3 -fwasm-exceptions -s USE_SDL=2 -s USE_ZLIB=1 -DBOXEDWINE_ZLIB -DSDL2=1 -DBOXEDWINE_DISABLE_UI -DSIMDE_SSE2_NO_NATIVE $(GCC_EXTRA_FLAGS) -Wall -Wno-deprecated-pragma -Wno-format-security -Wno-unused-private-field -Wno-invalid-offsetof -Wno-delete-incomplete -Wno-unused-result -Wno-unknown-pragmas -Wno-unused-local-typedefs -Wno-unused-variable -Wno-unused-function -Wno-unused-but-set-variable $(INCLUDES) $(EXTRA_CPP_FLAGS)
 
-LDFLAGS = -s FORCE_FILESYSTEM -lidbfs.js -s USE_SDL=2 -s USE_ZLIB=1 -fwasm-exceptions -s TOTAL_MEMORY=536870912 --shell-file $(SHELL_FILE) -s EXPORTED_RUNTIME_METHODS='["addRunDependency", "removeRunDependency","ERRNO_CODES"]' $(EXTRA_LD_FLAGS)
+LDFLAGS = -s FORCE_FILESYSTEM -lidbfs.js -s USE_SDL=2 -s USE_ZLIB=1 -fwasm-exceptions -s TOTAL_MEMORY=536870912 -sALLOW_MEMORY_GROWTH=1 -sMAXIMUM_MEMORY=1073741824 --shell-file $(SHELL_FILE) -s EXPORTED_RUNTIME_METHODS='["addRunDependency", "removeRunDependency","ERRNO_CODES"]' $(EXTRA_LD_FLAGS)
 
 #$(TEST_BUILD_DIR)/boxedwineTest: $(TEST_OBJS)
 #	$(CC) $(TEST_OBJS) -o $@ $(LDFLAGS)
diff --git i/source/io/fsfilenode.cpp w/source/io/fsfilenode.cpp
index 2cf9d94..52b46da 100644
--- i/source/io/fsfilenode.cpp
+++ w/source/io/fsfilenode.cpp
@@ -82,7 +82,7 @@ bool FsFileNode::remove() {
     }
 #ifdef BOXEDWINE_ZLIB
     if (zipNode) {
-        std::shared_ptr<FsZip> fsZip = zipNode->fsZip.lock();
+        std::shared_ptr<FsZip> fsZip = zipNode->fsZip;
         if (fsZip) {
             fsZip->remove(this->path);
         }
@@ -405,7 +405,7 @@ U32 FsFileNode::rename(BString path) {
             this->removeNodeFromParent();
 #ifdef BOXEDWINE_ZLIB
             if (zipNode) {
-                std::shared_ptr<FsZip> fsZip = zipNode->fsZip.lock();
+                std::shared_ptr<FsZip> fsZip = zipNode->fsZip;
                 if (fsZip) {
                     fsZip->remove(this->path);
                 }
diff --git i/source/io/fszipnode.h w/source/io/fszipnode.h
index 7492198..581ca62 100644
--- i/source/io/fszipnode.h
+++ w/source/io/fszipnode.h
@@ -34,7 +34,8 @@ public:
     FsOpenNode* open(std::shared_ptr<FsNode> node, U32 flags);
     bool moveToFileSystem(std::shared_ptr<FsNode> node);
 
-    std::weak_ptr<FsZip> fsZip;
+    // ZIP-backed nodes retain their archive across the asynchronous browser loop.
+    std::shared_ptr<FsZip> fsZip;
 private:
     fsZipInfo zipInfo;
 };
diff --git i/source/io/fszipopennode.cpp w/source/io/fszipopennode.cpp
index f6f062f..f59ac0b 100644
--- i/source/io/fszipopennode.cpp
+++ w/source/io/fszipopennode.cpp
@@ -93,7 +93,7 @@ bool FsZipOpenNode::canMap() {
 U32 FsZipOpenNode::readNative(U8* buffer, U32 len) {
     U32 result = 0;
     BOXEDWINE_CRITICAL_SECTION_WITH_MUTEX(*getReadMutex());
-    std::shared_ptr<FsZip> fsZip = zipNode->fsZip.lock();
+    std::shared_ptr<FsZip> fsZip = zipNode->fsZip;
     if (fsZip) {
         fsZip->setupZipRead(this->offset, this->pos);
         result = unzReadCurrentFile(fsZip->zipfile, buffer, len);
@@ -113,7 +113,7 @@ void FsZipOpenNode::reopen() {
 }
 
 BOXEDWINE_MUTEX* FsZipOpenNode::getReadMutex() {
-    std::shared_ptr<FsZip> fsZip = zipNode->fsZip.lock();
+    std::shared_ptr<FsZip> fsZip = zipNode->fsZip;
     if (fsZip) {
         return &fsZip->readMutex;
     }
diff --git i/source/kernel/kscheduler.cpp w/source/kernel/kscheduler.cpp
index b1192a5..3119b6e 100644
--- i/source/kernel/kscheduler.cpp
+++ w/source/kernel/kscheduler.cpp
@@ -134,8 +134,8 @@ void runThreadSlice(KThread* thread) {
     cpu = thread->cpu;
     cpu->blockInstructionCount = 0;
     cpu->yield = false;
-    cpu->nextOp = cpu->getNextOp(); // another thread that just ran could have modified this
     try {
+        cpu->nextOp = cpu->getNextOp(); // another thread that just ran could have modified this
         do {
             cpu->run();
         } while ((int)cpu->blockInstructionCount < contextTimeRemaining && !cpu->yield);