Application testing: using multiple users in Oracle instead of mem H2. How to make it as fast as possible?

I decided to stop using H2 for obvious reasons (I have Oracle on production, compatibility mode is a fake). So, I wrote simple test framework which for each test in my application does the following:

1. 
   

   Generate random username (in example below it's test_user).

   
   


2. 
   

   Create new user and tablespace:

   
   

   create tablespace test_user_ts datafile 'test_user_tabspace.dat' size 10M reuse autoextend on next 500K;

   
   

   create temporary tablespace test_user_ts_tmp tempfile 'test_user.tabspace_temp.dat' size 10M reuse autoextend on next 500K;

   
   

   create user test_user identified by test_password default tablespace test_user_ts temporary tablespace test_user_ts_tmp;

   
   

   grant create session to test_user;

   
   

   grant all privileges to test_user;

   
   


3. 
   

   Populate database with test data.

   
   


4. 
   

   Run test.

   
   


5. 
   

   Clean up:

   
   

   drop user test_user cascade;

   
   

   drop tablespace test_user_ts_tmp;

   
   

   drop tablespace test_user_ts;

   
   

The problem is that stages 1-3 are slow. How can I make them as fast as possible? Is there maybe any way of copying existing db schema to another one?

Db version: Oracle 11g

I have full control over Oracle instance. It runs on a vagrant image on my dev machine.