Reproduction steps:

1. Open "TestAndroid64bit.zip" project
2. "Custom" -> "Build AssetBundle Android"
3. "Custom" -> "Build Player Android32Bit (Release)"
4. "Custom" -> "Build Player Android64Bit (Release)"
5. Launch the 32Bit App and note the time it takes to execute at the bottom of the screen
6. Launch the 64Bit App and note the time it takes to execute at the bottom of the screen
7. Compare the times

Expected Result: 32Bit/64Bit takes around the same amount of time
Actual Result: 64Bit takes at least two times more that 32Bit

Reproduced with: 2019.3.0a7, 2019.2.0a7, 2019.1.8f1, 2018.4.3f1, 2017.4.29f1

Note:
The issue is way more noticeable on lower end devices, they can get affected x10+

Google Pixel 2 XL:
No Compression: 32Bit - ~1.25 seconds; 64Bit - ~2.5 seconds;
LZMA: 32Bit - 1.25-1.3 seconds; 64Bit - ~2.5seconds;
LZ4: 32Bit - 1.3 seconds; 64Bit - ~2.5 seconds;

Repro Devices:
VLNQA00123, Google Pixel 2 XL (Pixel 2 XL), Android 9, CPU: Snapdragon 835 MSM8998, GPU: Adreno (TM) 540
VLNQA00218, Samsung Galaxy Note9 (SM-N960U), Android 8.1.0, CPU: Snapdragon 845 SDM845, GPU: Adreno (TM) 630
VLNQA00224, Samsung Galaxy A5(2017) (SM-A520F), Android 8.0.0, CPU: Exynos 7 Octa 7880, GPU: Mali-T830
VLNQA00005, Samsung Galaxy S7 (SM-G930V), Android 7.0, CPU: Snapdragon 820 MSM8996, GPU: Adreno (TM) 530
VLNQA00004, Meizu - (MX5), Android 5.0.1, CPU: MediaTek Helio X10 MT6795T, GPU: PowerVR Rogue G6200
VLNQA00052, Xiaomi MI MAX (MI MAX), Android 7.0, CPU: Snapdragon 617 MSM8952, GPU: Adreno (TM) 510