diff --git a/performanceDb/src/main/java/org/lucares/performance/db/PdbWriter.java b/performanceDb/src/main/java/org/lucares/performance/db/PdbWriter.java
index 072a96b..fcd1fcf 100644
--- a/performanceDb/src/main/java/org/lucares/performance/db/PdbWriter.java
+++ b/performanceDb/src/main/java/org/lucares/performance/db/PdbWriter.java
@@ -105,6 +105,10 @@ class PdbWriter implements AutoCloseable, Flushable {
 	public OffsetDateTime getDateOffset() {
 		return DateUtils.epochMilliInUTC(lastEpochMilli);
 	}
+	
+	public long getDateOffsetAsEpochMilli() {
+		return lastEpochMilli;
+	}
 
 	public void write(final Entry entry) throws WriteException, InvalidValueException {
 		final long epochMilli = entry.getEpochMilli();
diff --git a/performanceDb/src/main/java/org/lucares/performance/db/PdbWriterByTimeAsc.java b/performanceDb/src/main/java/org/lucares/performance/db/PdbWriterByTimeAsc.java
index d5cae4c..e5153a5 100644
--- a/performanceDb/src/main/java/org/lucares/performance/db/PdbWriterByTimeAsc.java
+++ b/performanceDb/src/main/java/org/lucares/performance/db/PdbWriterByTimeAsc.java
@@ -1,6 +1,5 @@
 package org.lucares.performance.db;
 
-import java.time.OffsetDateTime;
 import java.util.Comparator;
 
 public class PdbWriterByTimeAsc implements Comparator<PdbWriter> {
@@ -11,9 +10,9 @@ public class PdbWriterByTimeAsc implements Comparator<PdbWriter> {
 	@Override
 	public int compare(final PdbWriter o1, final PdbWriter o2) {
 
-		final OffsetDateTime o1From = o1.getDateOffset();
-		final OffsetDateTime o2From = o2.getDateOffset();
-		return o1From.compareTo(o2From);
+		final long o1From = o1.getDateOffsetAsEpochMilli();
+		final long o2From = o2.getDateOffsetAsEpochMilli();
+		return Long.compare(o1From, o2From);
 	}
 
 }
diff --git a/performanceDb/src/main/java/org/lucares/performance/db/PerformanceDb.java b/performanceDb/src/main/java/org/lucares/performance/db/PerformanceDb.java
index 4722960..4e515ae 100644
--- a/performanceDb/src/main/java/org/lucares/performance/db/PerformanceDb.java
+++ b/performanceDb/src/main/java/org/lucares/performance/db/PerformanceDb.java
@@ -81,9 +81,9 @@ public class PerformanceDb implements AutoCloseable {
 				try {
 
 					final Tags tags = entry.getTags();
-					final OffsetDateTime date = entry.getDate();
+					final long dateAsEpochMilli = entry.getEpochMilli();
 
-					final PdbWriter writer = tagsToFile.getWriter(date, tags);
+					final PdbWriter writer = tagsToFile.getWriter(dateAsEpochMilli, tags);
 
 					writer.write(entry);
 					count++;
diff --git a/performanceDb/src/main/java/org/lucares/performance/db/TagsToFile.java b/performanceDb/src/main/java/org/lucares/performance/db/TagsToFile.java
index c29c00b..f4703fd 100644
--- a/performanceDb/src/main/java/org/lucares/performance/db/TagsToFile.java
+++ b/performanceDb/src/main/java/org/lucares/performance/db/TagsToFile.java
@@ -80,17 +80,16 @@ public class TagsToFile implements AutoCloseable {
 		return result;
 	}
 
-	public PdbWriter getWriter(final OffsetDateTime date, final Tags tags) throws ReadException, WriteException {
+	public PdbWriter getWriter(final long dateAsEpochMilli, final Tags tags) throws ReadException, WriteException {
 		final PdbWriter result;
 		final WriterCache writersForTags = getOrInit(tags);
 
-		final Optional<PdbWriter> optionalWriter = chooseBestMatchingWriter(writersForTags.getWriters(), date);
+		final Optional<PdbWriter> optionalWriter = chooseBestMatchingWriter(writersForTags.getWriters(), dateAsEpochMilli);
 
 		if (optionalWriter.isPresent()) {
 			result = optionalWriter.get();
 			LOGGER.trace("using existing pdbWriter: {}", result);
 		} else {
-			final long start = System.nanoTime();
 			final List<PdbFile> pdbFiles = getFilesMatchingTagsExactly(tags);
 
 			pdbFiles.removeIf(f -> !f.exists());
@@ -99,10 +98,7 @@ public class TagsToFile implements AutoCloseable {
 					Optional::isPresent);
 			final List<PdbWriter> writers = CollectionUtils.map(existingWriters, Optional::get);
 			
-			METRICS_LOGGER_FIND_WRITER.debug("find writers took {}ms for tags {}", (System.nanoTime() - start)
-					/ 1_000_000.0, tags);
-
-			final Optional<PdbWriter> optionalFirst = chooseBestMatchingWriter(writers, date);
+			final Optional<PdbWriter> optionalFirst = chooseBestMatchingWriter(writers, dateAsEpochMilli);
 
 			result = optionalFirst.orElseGet(() -> newPdbWriter(tags));
 			LOGGER.debug("create new pdbWriter: {}", result);
@@ -110,14 +106,14 @@ public class TagsToFile implements AutoCloseable {
 		return result;
 	}
 
-	private Optional<PdbWriter> chooseBestMatchingWriter(final List<PdbWriter> writers, final OffsetDateTime date) {
+	private Optional<PdbWriter> chooseBestMatchingWriter(final List<PdbWriter> writers, final long dateAsEpochMilli) {
 
 		Collections.sort(writers, PdbWriterByTimeAsc.REVERSED);
 
 		for (final PdbWriter pdbWriter : writers) {
-			final OffsetDateTime offsetTime = pdbWriter.getDateOffset();
+			final long offsetTime = pdbWriter.getDateOffsetAsEpochMilli();
 
-			if (!date.isBefore(offsetTime)) {
+			if (dateAsEpochMilli >= offsetTime) {
 				return Optional.of(pdbWriter);
 			}
 		}
@@ -126,11 +122,13 @@ public class TagsToFile implements AutoCloseable {
 
 	private WriterCache getOrInit(final Tags tags) {
 
-		if (!cachedWriters.containsKey(tags)) {
-			cachedWriters.put(tags, new WriterCache());
+		WriterCache result = cachedWriters.get(tags);
+		if (result == null) {
+			result = new WriterCache();
+			cachedWriters.put(tags, result);
 		}
 
-		return cachedWriters.get(tags);
+		return result;
 	}
 
 	public void clearWriterCache() {
diff --git a/performanceDb/src/test/java/org/lucares/performance/db/TagsToFilesTest.java b/performanceDb/src/test/java/org/lucares/performance/db/TagsToFilesTest.java
index 10a6673..8eeabf1 100644
--- a/performanceDb/src/test/java/org/lucares/performance/db/TagsToFilesTest.java
+++ b/performanceDb/src/test/java/org/lucares/performance/db/TagsToFilesTest.java
@@ -37,9 +37,9 @@ public class TagsToFilesTest {
 			final OffsetDateTime date = OffsetDateTime.now(ZoneOffset.UTC);
 			final Tags tags = Tags.create("myKey", "myValue");
 
-			final PdbWriter newFileForTags = tagsToFile.getWriter(date, tags);
+			final PdbWriter newFileForTags = tagsToFile.getWriter(date.toInstant().toEpochMilli(), tags);
 
-			final PdbWriter existingFileForTags = tagsToFile.getWriter(date, tags);
+			final PdbWriter existingFileForTags = tagsToFile.getWriter(date.toInstant().toEpochMilli(), tags);
 
 			Assert.assertSame(newFileForTags, existingFileForTags);
 		}
@@ -54,9 +54,9 @@ public class TagsToFilesTest {
 
 			final Tags tags = Tags.create("myKey", "myValue");
 
-			final PdbWriter writerForDay1 = tagsToFile.getWriter(day1, tags);
+			final PdbWriter writerForDay1 = tagsToFile.getWriter(day1.toInstant().toEpochMilli(), tags);
 			writerForDay1.write(new Entry(day1, 1, tags));
-			final PdbWriter writerForDay2 = tagsToFile.getWriter(day2, tags);
+			final PdbWriter writerForDay2 = tagsToFile.getWriter(day2.toInstant().toEpochMilli(), tags);
 			writerForDay2.write(new Entry(day2, 2, tags));
 
 			Assert.assertSame(writerForDay1, writerForDay2);
@@ -76,22 +76,22 @@ public class TagsToFilesTest {
 
 			final Tags tags = Tags.create("myKey", "myValue");
 
-			final PdbWriter writerAfternoon = tagsToFile.getWriter(afternoon, tags);
+			final PdbWriter writerAfternoon = tagsToFile.getWriter(afternoon.toInstant().toEpochMilli(), tags);
 			writerAfternoon.write(new Entry(afternoon, 1, tags));
 
-			final PdbWriter writerMorning = tagsToFile.getWriter(morning, tags);
+			final PdbWriter writerMorning = tagsToFile.getWriter(morning.toInstant().toEpochMilli(), tags);
 			writerMorning.write(new Entry(morning, 2, tags));
 
 			Assert.assertNotSame(writerAfternoon, writerMorning);
 			Assert.assertNotEquals(writerAfternoon.getPdbFile(), writerMorning.getPdbFile());
 
-			final PdbWriter writerEarlyMorning = tagsToFile.getWriter(earlyMorning, tags);
+			final PdbWriter writerEarlyMorning = tagsToFile.getWriter(earlyMorning.toInstant().toEpochMilli(), tags);
 			writerEarlyMorning.write(new Entry(earlyMorning, 3, tags));
 
 			Assert.assertNotSame(writerEarlyMorning, writerAfternoon);
 			Assert.assertNotSame(writerEarlyMorning, writerMorning);
 
-			final PdbWriter writerEvening = tagsToFile.getWriter(evening, tags);
+			final PdbWriter writerEvening = tagsToFile.getWriter(evening.toInstant().toEpochMilli(), tags);
 
 			Assert.assertSame(writerEvening, writerAfternoon,
 					"the evening event can be appended to the afternoon file");
@@ -111,10 +111,10 @@ public class TagsToFilesTest {
 
 			final Tags tags = Tags.create("myKey", "myValue");
 
-			final PdbWriter fileA = tagsToFile.getWriter(timestamp, tags);
+			final PdbWriter fileA = tagsToFile.getWriter(timestamp.toInstant().toEpochMilli(), tags);
 			fileA.write(new Entry(timestamp, 1, tags));
 
-			final PdbWriter fileB = tagsToFile.getWriter(timestamp, tags);
+			final PdbWriter fileB = tagsToFile.getWriter(timestamp.toInstant().toEpochMilli(), tags);
 			fileA.write(new Entry(timestamp, 2, tags));
 
 			Assert.assertEquals(fileA, fileB);