diff --git a/COPYING_NOTES.md b/COPYING_NOTES.md
index a54faf11..b9af649d 100644
--- a/COPYING_NOTES.md
+++ b/COPYING_NOTES.md
@@ -56,6 +56,7 @@ Proton Mail Bridge includes the following 3rd party software:
 * [logrus](https://github.com/sirupsen/logrus) available under [license](https://github.com/sirupsen/logrus/blob/master/LICENSE) 
 * [testify](https://github.com/stretchr/testify) available under [license](https://github.com/stretchr/testify/blob/master/LICENSE) 
 * [cli](https://github.com/urfave/cli/v2) available under [license](https://github.com/urfave/cli/v2/blob/master/LICENSE) 
+* [msgpack](https://github.com/vmihailenco/msgpack/v5) available under [license](https://github.com/vmihailenco/msgpack/v5/blob/master/LICENSE) 
 * [liteapi](https://gitlab.protontech.ch/go/liteapi)
 * [goleak](https://go.uber.org/goleak)
 * [exp](https://golang.org/x/exp) available under [license](https://cs.opensource.google/go/x/exp/+/master:LICENSE) 
@@ -120,6 +121,7 @@ Proton Mail Bridge includes the following 3rd party software:
 * [pflag](https://github.com/spf13/pflag) available under [license](https://github.com/spf13/pflag/blob/master/LICENSE) 
 * [bom](https://github.com/ssor/bom) available under [license](https://github.com/ssor/bom/blob/master/LICENSE) 
 * [codec](https://github.com/ugorji/go/codec) available under [license](https://github.com/ugorji/go/codec/blob/master/LICENSE) 
+* [tagparser](https://github.com/vmihailenco/tagparser/v2) available under [license](https://github.com/vmihailenco/tagparser/v2/blob/master/LICENSE) 
 * [smetrics](https://github.com/xrash/smetrics) available under [license](https://github.com/xrash/smetrics/blob/master/LICENSE) 
 * [go-cty](https://github.com/zclconf/go-cty) available under [license](https://github.com/zclconf/go-cty/blob/master/LICENSE) 
 * [crypto](https://golang.org/x/crypto) available under [license](https://cs.opensource.google/go/x/crypto/+/master:LICENSE) 
diff --git a/go.mod b/go.mod
index a32e83e1..4ed4b968 100644
--- a/go.mod
+++ b/go.mod
@@ -38,6 +38,7 @@ require (
 	github.com/sirupsen/logrus v1.9.0
 	github.com/stretchr/testify v1.8.0
 	github.com/urfave/cli/v2 v2.20.3
+	github.com/vmihailenco/msgpack/v5 v5.3.5
 	gitlab.protontech.ch/go/liteapi v0.36.1
 	go.uber.org/goleak v1.2.0
 	golang.org/x/exp v0.0.0-20221023144134-a1e5550cf13e
@@ -105,6 +106,7 @@ require (
 	github.com/spf13/pflag v1.0.5 // indirect
 	github.com/ssor/bom v0.0.0-20170718123548-6386211fdfcf // indirect
 	github.com/ugorji/go/codec v1.2.7 // indirect
+	github.com/vmihailenco/tagparser/v2 v2.0.0 // indirect
 	github.com/xrash/smetrics v0.0.0-20201216005158-039620a65673 // indirect
 	github.com/zclconf/go-cty v1.11.0 // indirect
 	golang.org/x/crypto v0.1.0 // indirect
diff --git a/go.sum b/go.sum
index 508e5bff..8bf4ab37 100644
--- a/go.sum
+++ b/go.sum
@@ -393,6 +393,10 @@ github.com/ugorji/go/codec v1.2.7 h1:YPXUKf7fYbp/y8xloBqZOw2qaVggbfwMlI8WM3wZUJ0
 github.com/ugorji/go/codec v1.2.7/go.mod h1:WGN1fab3R1fzQlVQTkfxVtIBhWDRqOviHU95kRgeqEY=
 github.com/urfave/cli/v2 v2.20.3 h1:lOgGidH/N5loaigd9HjFsOIhXSTrzl7tBpHswZ428w4=
 github.com/urfave/cli/v2 v2.20.3/go.mod h1:1CNUng3PtjQMtRzJO4FMXBQvkGtuYRxxiR9xMa7jMwI=
+github.com/vmihailenco/msgpack/v5 v5.3.5 h1:5gO0H1iULLWGhs2H5tbAHIZTV8/cYafcFOr9znI5mJU=
+github.com/vmihailenco/msgpack/v5 v5.3.5/go.mod h1:7xyJ9e+0+9SaZT0Wt1RGleJXzli6Q/V5KbhBonMG9jc=
+github.com/vmihailenco/tagparser/v2 v2.0.0 h1:y09buUbR+b5aycVFQs/g70pqKVZNBmxwAhO7/IwNM9g=
+github.com/vmihailenco/tagparser/v2 v2.0.0/go.mod h1:Wri+At7QHww0WTrCBeu4J6bNtoV6mEfg5OIWRZA9qds=
 github.com/xiang90/probing v0.0.0-20190116061207-43a291ad63a2/go.mod h1:UETIi67q53MR2AWcXfiuqkDkRtnGDLqkBTpCHuJHxtU=
 github.com/xrash/smetrics v0.0.0-20201216005158-039620a65673 h1:bAn7/zixMGCfxrRTfdpNzjtPYqr8smhKouy9mxVdGPU=
 github.com/xrash/smetrics v0.0.0-20201216005158-039620a65673/go.mod h1:N3UwUGtsrSj3ccvlPHLoLsHnpR27oXr4ZE984MbSER8=
diff --git a/internal/vault/settings.go b/internal/vault/settings.go
index 239a9a16..e3e50b3b 100644
--- a/internal/vault/settings.go
+++ b/internal/vault/settings.go
@@ -168,13 +168,13 @@ func (vault *Vault) SetAutoUpdate(autoUpdate bool) error {
 
 // GetLastVersion returns the last version of the bridge that was run.
 func (vault *Vault) GetLastVersion() *semver.Version {
-	return vault.get().Settings.LastVersion
+	return semver.MustParse(vault.get().Settings.LastVersion)
 }
 
 // SetLastVersion sets the last version of the bridge that was run.
 func (vault *Vault) SetLastVersion(version *semver.Version) error {
 	return vault.mod(func(data *Data) {
-		data.Settings.LastVersion = version
+		data.Settings.LastVersion = version.String()
 	})
 }
 
diff --git a/internal/vault/types.go b/internal/vault/types.go
index b760ff89..976bbb34 100644
--- a/internal/vault/types.go
+++ b/internal/vault/types.go
@@ -20,7 +20,6 @@ package vault
 import (
 	"math/rand"
 
-	"github.com/Masterminds/semver/v3"
 	"github.com/ProtonMail/gluon/imap"
 	"github.com/ProtonMail/proton-bridge/v2/internal/updater"
 )
@@ -58,7 +57,7 @@ type Settings struct {
 	Autostart    bool
 	AutoUpdate   bool
 
-	LastVersion   *semver.Version
+	LastVersion   string
 	FirstStart    bool
 	FirstStartGUI bool
 }
@@ -81,7 +80,7 @@ func newDefaultSettings(gluonDir string) Settings {
 		Autostart:    false,
 		AutoUpdate:   true,
 
-		LastVersion:   semver.MustParse("0.0.0"),
+		LastVersion:   "0.0.0",
 		FirstStart:    true,
 		FirstStartGUI: true,
 	}
diff --git a/internal/vault/vault.go b/internal/vault/vault.go
index 20dc37f0..9d11ae48 100644
--- a/internal/vault/vault.go
+++ b/internal/vault/vault.go
@@ -22,7 +22,6 @@ import (
 	"crypto/cipher"
 	"crypto/rand"
 	"crypto/sha256"
-	"encoding/json"
 	"errors"
 	"fmt"
 	"io/fs"
@@ -32,6 +31,7 @@ import (
 
 	"github.com/ProtonMail/proton-bridge/v2/internal/certs"
 	"github.com/bradenaw/juniper/xslices"
+	"github.com/vmihailenco/msgpack/v5"
 )
 
 // Vault is an encrypted data vault that stores bridge and user data.
@@ -253,7 +253,7 @@ func (vault *Vault) get() Data {
 
 	var data Data
 
-	if err := json.Unmarshal(dec, &data); err != nil {
+	if err := msgpack.Unmarshal(dec, &data); err != nil {
 		panic(err)
 	}
 
@@ -271,13 +271,13 @@ func (vault *Vault) mod(fn func(data *Data)) error {
 
 	var data Data
 
-	if err := json.Unmarshal(dec, &data); err != nil {
+	if err := msgpack.Unmarshal(dec, &data); err != nil {
 		return err
 	}
 
 	fn(&data)
 
-	mod, err := json.Marshal(data)
+	mod, err := msgpack.Marshal(data)
 	if err != nil {
 		return err
 	}
@@ -314,7 +314,7 @@ func initVault(path, gluonDir string, gcm cipher.AEAD) ([]byte, error) {
 		return nil, err
 	}
 
-	dec, err := json.Marshal(Data{
+	dec, err := msgpack.Marshal(Data{
 		Settings: newDefaultSettings(gluonDir),
 
 		Certs: Certs{
diff --git a/internal/vault/vault_bench_test.go b/internal/vault/vault_bench_test.go
new file mode 100644
index 00000000..1596211d
--- /dev/null
+++ b/internal/vault/vault_bench_test.go
@@ -0,0 +1,58 @@
+// Copyright (c) 2022 Proton AG
+//
+// This file is part of Proton Mail Bridge.
+//
+// Proton Mail Bridge is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Proton Mail Bridge is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Proton Mail Bridge.  If not, see <https://www.gnu.org/licenses/>.
+
+package vault_test
+
+import (
+	"bytes"
+	"testing"
+
+	"github.com/ProtonMail/proton-bridge/v2/internal/vault"
+	"github.com/google/uuid"
+	"github.com/stretchr/testify/require"
+)
+
+func BenchmarkVault(b *testing.B) {
+	vaultDir, gluonDir := b.TempDir(), b.TempDir()
+
+	// Create a new vault.
+	s, corrupt, err := vault.New(vaultDir, gluonDir, []byte("my secret key"))
+	require.NoError(b, err)
+	require.False(b, corrupt)
+
+	// Add 10kB of cookies to the vault.
+	require.NoError(b, s.SetCookies(bytes.Repeat([]byte("a"), 10_000)))
+
+	// Create 10 vault users.
+	for idx := 0; idx < 10; idx++ {
+		user, err := s.AddUser(uuid.NewString(), "username", "authUID", "authRef", []byte("keyPass"))
+		require.NoError(b, err)
+
+		require.NoError(b, user.SetKeyPass([]byte("new key pass")))
+	}
+
+	b.ResetTimer()
+
+	// Time how quickly we can iterate through the users and get their key pass and bridge pass.
+	for i := 0; i < b.N; i++ {
+		require.NoError(b, s.ForUser(func(user *vault.User) error {
+			require.NotEmpty(b, user.KeyPass())
+			require.NotEmpty(b, user.BridgePass())
+			return nil
+		}))
+	}
+}