diff --git a/backend/local/local.go b/backend/local/local.go
index 71b52b723..8c6f30d6a 100644
--- a/backend/local/local.go
+++ b/backend/local/local.go
@@ -817,6 +817,12 @@ func (o *Object) Update(in io.Reader, src fs.ObjectInfo, options ...fs.OpenOptio
 		return err
 	}
 
+	// Pre-allocate the file for performance reasons
+	err = preAllocate(src.Size(), out)
+	if err != nil {
+		fs.Debugf(o, "Failed to pre-allocate: %v", err)
+	}
+
 	// Calculate the hash of the object we are reading as we go along
 	hash, err := hash.NewMultiHasherTypes(hashes)
 	if err != nil {
diff --git a/backend/local/preallocate_other.go b/backend/local/preallocate_other.go
new file mode 100644
index 000000000..7afff5e29
--- /dev/null
+++ b/backend/local/preallocate_other.go
@@ -0,0 +1,10 @@
+//+build !windows
+
+package local
+
+import "os"
+
+// preAllocate the file for performance reasons
+func preAllocate(size int64, out *os.File) error {
+	return nil
+}
diff --git a/backend/local/preallocate_windows.go b/backend/local/preallocate_windows.go
new file mode 100644
index 000000000..dfd88369d
--- /dev/null
+++ b/backend/local/preallocate_windows.go
@@ -0,0 +1,79 @@
+//+build windows
+
+package local
+
+import (
+	"os"
+	"syscall"
+	"unsafe"
+
+	"github.com/pkg/errors"
+	"golang.org/x/sys/windows"
+)
+
+var (
+	ntdll                        = windows.NewLazySystemDLL("ntdll.dll")
+	ntQueryVolumeInformationFile = ntdll.NewProc("NtQueryVolumeInformationFile")
+	ntSetInformationFile         = ntdll.NewProc("NtSetInformationFile")
+)
+
+type fileAllocationInformation struct {
+	AllocationSize uint64
+}
+
+type fileFsSizeInformation struct {
+	TotalAllocationUnits     uint64
+	AvailableAllocationUnits uint64
+	SectorsPerAllocationUnit uint32
+	BytesPerSector           uint32
+}
+
+type ioStatusBlock struct {
+	Status, Information uintptr
+}
+
+// preAllocate the file for performance reasons
+func preAllocate(size int64, out *os.File) error {
+	if size <= 0 {
+		return nil
+	}
+
+	var (
+		iosb       ioStatusBlock
+		fsSizeInfo fileFsSizeInformation
+		allocInfo  fileAllocationInformation
+	)
+
+	// Query info about the block sizes on the file system
+	_, _, e1 := ntQueryVolumeInformationFile.Call(
+		uintptr(out.Fd()),
+		uintptr(unsafe.Pointer(&iosb)),
+		uintptr(unsafe.Pointer(&fsSizeInfo)),
+		uintptr(unsafe.Sizeof(fsSizeInfo)),
+		uintptr(3), // FileFsSizeInformation
+	)
+	if e1 != nil && e1 != syscall.Errno(0) {
+		return errors.Wrap(e1, "preAllocate NtQueryVolumeInformationFile failed")
+	}
+
+	// Calculate the allocation size
+	clusterSize := uint64(fsSizeInfo.BytesPerSector) * uint64(fsSizeInfo.SectorsPerAllocationUnit)
+	if clusterSize <= 0 {
+		return errors.Errorf("preAllocate clusterSize %d <= 0", clusterSize)
+	}
+	allocInfo.AllocationSize = (1 + uint64(size-1)/clusterSize) * clusterSize
+
+	// Ask for the allocation
+	_, _, e1 = ntSetInformationFile.Call(
+		uintptr(out.Fd()),
+		uintptr(unsafe.Pointer(&iosb)),
+		uintptr(unsafe.Pointer(&allocInfo)),
+		uintptr(unsafe.Sizeof(allocInfo)),
+		uintptr(19), // FileAllocationInformation
+	)
+	if e1 != nil && e1 != syscall.Errno(0) {
+		return errors.Wrap(e1, "preAllocate NtSetInformationFile failed")
+	}
+
+	return nil
+}