Neo4j import runtime issue - neo4j

Question

I am trying to import a design with 230M Nodes, 300M relationships and 1.5B properties overall.
It takes nearly 5.5 hours to import the design. Wondering how to improve the runtime.
If i analyze the messages from Neo4j import, it takes quite a bit of time in relationship -> relationship. Not sure as what it does here.
Any suggestion to improve the load time:
My run command is :
/home/neo4j-enterprise-3.3.2/bin/neo4j-admin import --nodes "./instances." --relationships:SIGN_OF "./sign." --relationships:RIN_OF "./rin.* --id-type=INTEGER --database graph.db;
My heap initial and max size is set to 32G
Instance header:
NodeId:ID,:IGNORE,:Label,Din:int,LGit:int,RGit:int,Signed:int,Cens,Type,:IGNORE,Val:Float
Signal Header:
:IGNORE,:IGNORE,LGit:int,RGit:int,Signed:int,:IGNORE,:START_ID,:END_ID
Rin header
:START_ID,:END_ID,:IGNORE
Neo4j import output
Available resources:
Total machine memory: 504.70 GB
Free machine memory: 88.71 GB
Max heap memory : 26.67 GB
Processors: 16
Configured max memory: 55.84 GB
Nodes, started 2018-04-09 17:52:36.028+0000
[>:|NODE:1.75 GB--------------|PROPERTIES(3)=====|LABEL |*v:87.95 MB/s(4)=====================] 234M ∆ 819K
Done in 4m 13s 984ms
Prepare node index, started 2018-04-09 17:56:50.351+0000
[*DETECT:2.62 GB------------------------------------------------------------------------------] 234M ∆71.2M30000
Done in 33s 546ms
Relationships, started 2018-04-09 17:57:23.935+0000
[>||PREPARE-----------------------------------|||*v:20.96 MB/s(16)============================] 303M ∆ 256K
Done in 7m 7s 922ms
Node Degrees, started 2018-04-09 18:04:37.914+0000
[*>(16)=============================================================================|CALCULATE] 303M ∆1.97M
Done in 1m 30s 566ms
Relationship --> Relationship 1-2/2, started 2018-04-09 18:06:08.951+0000
[*>------------------------------------------------------------------------------------------|] 303M ∆ 144K
Done in 2h 8m 4s 36ms
RelationshipGroup 1-2/2, started 2018-04-09 20:14:13.059+0000
[>:4.44 MB/s----------|*v:2.22 MB/s(2)========================================================] 186K ∆9.81K
Done in 2s 105ms
Node --> Relationship, started 2018-04-09 20:14:15.178+0000
[*>------------------------------------------------------------------------------------------|] 234M ∆76.4K
Done in 27m 53s 408ms
Relationship --> Relationship 1-2/2, started 2018-04-09 20:42:08.654+0000
[*>------------------------------------------------------------------------------------------|] 303M ∆36.0K
Done in 2h 33m 24s 201ms
Count groups, started 2018-04-09 23:15:33.152+0000
[*>(16)=======================================================================================] 186K ∆59.8K
Done in 3s 898ms
Gather, started 2018-04-09 23:15:41.513+0000
[>(6)===|*CACHE-------------------------------------------------------------------------------] 186K ∆ 186K
Done in 322ms
Write, started 2018-04-09 23:15:41.859+0000
[>:1.30 |*v:1.11 MB/s(16)=====================================================================] 186K ∆21.2K
Done in 4s 161ms
Node --> Group, started 2018-04-09 23:15:46.117+0000
[*FIRST---------------------------------------------------------------------------------------] 148K ∆1.09K
Done in 4m 8s 747ms
Node counts, started 2018-04-09 23:19:55.032+0000
[*>(16)===========================================================|COUNT:1.79 GB--------------] 234M ∆4.63M
Done in 3m 33s 201ms
Relationship counts, started 2018-04-09 23:23:28.254+0000
[*>(16)===================================================================|COUNT--------------] 303M ∆ 450K
Done in 1m 29s 457ms
IMPORT DONE in 5h 32m 23s 509ms.
Imported:
234425118 nodes
303627293 relationships
1496022710 properties
Peak memory usage: 2.69 GB