Different results for same query with Native Script

ES Version 2.1.2
I am using NativeScript to filter documents by term value. The script returns true/false based on the lookup of the term value from the document. The number of results returned by Elasticsearch grows steadily for the same query until it reaches the actual count. I am not sure if it is because the fielddata is cached progressively. This always happens when ES is restarted. If the script query is replaced with terms query, the results are accurate in the first search. I also notice my custom script gets initialized multiple times and the number varies for every search request. What is wrong here?

I am running ES in single node with 3 shards and 0 replicas. The Native Script gets initialized 6 times for the first query. The number of initialization increases to somewhere 18 for second time for the same query and reaches to 22 for the third time. It stays on to 22 times for subsequent searches. As the number of initialization of Native Script increases I get more results for the same query and when it reaches the final count, actual number of search results is returned. Cant understand this inconsistency in total count of search results for the same query.

Found the issue. Search timeout was set to 500ms and during the first query (after bouncing ES), ES tries to load fielddata in memory from all active segments.Since initial population of fielddata took more time than the timeout threshold, fielddata from some segments were not loaded into memory. During subsequent searches, fielddata gets loaded completely and hence see actual count after few searches.
Increasing the timeout to 5s gave enough time to load fielddata from all segments and thereby getting actual total count in the first search itself.