fix null pointer exception

filename were generated without '$', but the parsing code expected
the '$'.

performanceDb/src/main/java/org/lucares/performance/db/PerformanceDb.java

@@ -63,7 +63,7 @@ public class PerformanceDb implements AutoCloseable {
 
 	public void put(final BlockingIterator<Entry> entries) throws WriteException {
 
-		final Duration timeBetweenSyncs = Duration.ofSeconds(1);
+		final Duration timeBetweenSyncs = Duration.ofSeconds(10);
 		long count = 0;
 		long insertionsSinceLastSync = 0;