Slow read times for ADS1115 over I2C

I have 4 analogue sensors attached to two separate ADS1115 and I am attempting to sample them at 10Hz, however the read times over I2C are allowing just over 1Hz actual sample rate. Here are the read timings for each of the ADS1115 in ms:

First ADS1115 read time: 318819 microseconds. (3 analogue sensors attached)
Second ADS1115 read time: 425089 microseconds. (4 analogue sensors attached)

This is clearly indicative of something being wrong somewhere. Is there a useful code snippet that may help me set up the ADS1115 to communicate faster of I2C? Does the library support batching? 

Here is how I set up the devices:

//Set up the first ADC on 0x49

ads.setAddr_ADS1115(0x49); // 0x49

ads.setGain(eGAIN_TWOTHIRDS); // 2/3x gain

ads.setMode(eMODE_CONTIN); // continuous mode

ads.setRate(eRATE_860); // 128SPS (default)

//ads.setOSMode(eOSMODE_SINGLE); // Set to start a single-conversion

ads.init();

//Set up the second ADC on 0x48

ads.setAddr_ADS1115(0x48); // 0x48

ads.setGain(eGAIN_TWOTHIRDS); // 2/3x gain

ads.setMode(eMODE_CONTIN); // scontinuous mode

ads.setRate(eRATE_860); // 128SPS (default)

//ads.setOSMode(eOSMODE_SINGLE); // Set to start a single-conversion

ads.init();