diff --git a/build.sbt b/build.sbt
index a133392..ccd07c7 100644
--- a/build.sbt
+++ b/build.sbt
@@ -87,4 +87,5 @@ lazy val root = (project in file(".")).
       "org.apache.spark" %% "spark-sql" % "3.5.3" % Provided,
       "org.apache.spark" %% "spark-graphx" % "3.5.3" % Provided,
       "graphframes" % "graphframes" % "0.8.3-spark3.5-s_2.12" % Provided),
+    javaOptions ++= Seq("-Xms10g", "-Xmx10g", "-XX:+CMSClassUnloadingEnabled")
   )
diff --git a/src/test/scala/org/graphsense/utxo/TransformationTest.scala b/src/test/scala/org/graphsense/utxo/TransformationTest.scala
index 8be98e1..e67888c 100644
--- a/src/test/scala/org/graphsense/utxo/TransformationTest.scala
+++ b/src/test/scala/org/graphsense/utxo/TransformationTest.scala
@@ -98,7 +98,6 @@ class TransformationTest extends TestBase {
     t.computeAddressCluster(regInputs, addressIds, false)
       .sort(F.addressId)
       .persist()
-
   val clusterAddresses =
     t.computeClusterAddresses(addressClusterCoinjoin)
       .sort(F.clusterId, F.addressId)
@@ -135,6 +134,10 @@ class TransformationTest extends TestBase {
     t.computeClusterRelations(plainClusterRelations, exchangeRates).persist()
   val noClusterRelations = clusterRelations.count()
 
+  plainClusterRelations.unpersist()
+  clusterInputs.unpersist()
+  clusterOutputs.unpersist()
+  addresses.unpersist()
   val cluster =
     t.computeCluster(basicCluster, clusterRelations)
       .sort(F.clusterId)