diff --git a/src/main/kotlin/ru/dbotthepony/mc/otm/matter/MatterManager.kt b/src/main/kotlin/ru/dbotthepony/mc/otm/matter/MatterManager.kt
index 4c059ca97..f33755814 100644
--- a/src/main/kotlin/ru/dbotthepony/mc/otm/matter/MatterManager.kt
+++ b/src/main/kotlin/ru/dbotthepony/mc/otm/matter/MatterManager.kt
@@ -25,6 +25,15 @@ import ru.dbotthepony.mc.otm.core.integerDivisionUp
 import ru.dbotthepony.mc.otm.core.registryName
 import ru.dbotthepony.mc.otm.core.set
 import ru.dbotthepony.mc.otm.data.stream
+import java.util.stream.Stream
+
+private fun <T> Collection<T>.probablyParallelStream(): Stream<out T> {
+	if (size >= 400) {
+		return parallelStream()
+	}
+
+	return stream()
+}
 
 object MatterManager : SimpleJsonResourceReloadListener(GsonBuilder().setPrettyPrinting().disableHtmlEscaping().create(), "otm_matter") {
 	const val DIRECTORY = "otm_matter"
@@ -222,7 +231,7 @@ object MatterManager : SimpleJsonResourceReloadListener(GsonBuilder().setPrettyP
 			if (key != null) {
 				if (replaceIfExists) {
 					// search & replace in parallel, if possible
-					val replaced = registry.parallelStream().anyMatch {
+					val replaced = registry.probablyParallelStream().anyMatch {
 						if (it is MutableKeyEntry && it.key == key) {
 							if (!comparePriority || it.priority < priority!!) {
 								it.matter = matter
@@ -242,7 +251,7 @@ object MatterManager : SimpleJsonResourceReloadListener(GsonBuilder().setPrettyP
 						registry.add(MutableKeyEntry(key, mutableListOf(modifier), matter, complexity, priority ?: 0))
 					}
 				} else {
-					if (registry.parallelStream().anyMatch { it is MutableKeyEntry && it.key == key }) {
+					if (registry.probablyParallelStream().anyMatch { it is MutableKeyEntry && it.key == key }) {
 						fail { "Value with key $key already exists" }
 						return
 					}
@@ -252,7 +261,7 @@ object MatterManager : SimpleJsonResourceReloadListener(GsonBuilder().setPrettyP
 			} else {
 				if (replaceIfExists) {
 					// search & replace in parallel, if possible
-					val replaced = registry.parallelStream().anyMatch {
+					val replaced = registry.probablyParallelStream().anyMatch {
 						if (it is MutableTagEntry && it.tag == tag) {
 							if (!comparePriority || it.priority < priority!!) {
 								it.matter = matter
@@ -272,7 +281,7 @@ object MatterManager : SimpleJsonResourceReloadListener(GsonBuilder().setPrettyP
 						registry.add(MutableTagEntry(tag!!, mutableListOf(modifier), matter, complexity, priority ?: 0))
 					}
 				} else {
-					if (registry.parallelStream().anyMatch { it is MutableTagEntry && it.tag == tag }) {
+					if (registry.probablyParallelStream().anyMatch { it is MutableTagEntry && it.tag == tag }) {
 						fail { "Value with tag $tag already exists" }
 						return
 					}