VirtFS is slow (20MB/s) on MacOS with Ubuntu 24.04 guest

**BEFORE SUBMITTING YOUR ISSUE, PLEASE LOOK AT THE PINNED ISSUES AND USE THE SEARCH FUNCTION TO MAKE SURE IT IS NOT ALREADY REPORTED. ALWAYS COMMENT ON AN EXISTING ISSUE INSTEAD OF MAKING A NEW ONE.**

**Describe the issue**

Given a shared folder on the guest:
```
cat /etc/fstab
...
share /mnt/example 9p trans=virtio,version=9p2000.L,rw,_netdev,nofail
```

Write performance is slow (20 MB/s). This was discovered because other applications performed very poorly.
```
cd /mnt/example
dd bs=1M count=256 if=/dev/zero of=test
^C
181+0 records in
181+0 records out
189792256 bytes (190 MB, 181 MiB) copied, 9.77671 s, 19.4 MB/s
```

Is this the expected performance?

An identical setup using VMware Fusion (and their shared folder implementation, `fuse.vmhgfs-fuse`) has a speed of 1.1 GB/s.

**Configuration**
* UTM Version: 4.5.3
* macOS Version: 14.5
* Mac Chip (Intel, M1, ...): M1 Pro

**Crash log**

**Debug log**

**Upload VM**