Hi @chim3yy
Welcome to the community 
We are glad to know that you are interested in neo4j.
Indexing is kind of thumb rule in terms of performance in neo4j.whenever you perform some query on graph db , indexes are the first thing that will refer the total db hits by your query. when you have large amount of data then you can see the difference in performance and time with indexes.
for more info you can refer below blog .
When Neo4j creates an index, it creates a redundant copy of the data in the database. Therefore using an index will result in more disk space being utilized, plus slower writes to the disk.
Therefore, you need to weigh up these factors when deciding which data/properties to index.
Generally, it's a good idea to create an index when you know there's going to be a lot of data on certain nodes. Also, if you find queries are taking too long to return, adding an index may help.
Hope this help you in query.
please let me know if you required further details.
Cheers.