00:00:01.701762 Host RAM: 8192MB (8.0GB) total, 3638MB (3.5GB) available
...
00:00:01.807402 RamSize <integer> = 0x0000000100000000 (4 294 967 296, 4 096 MB, 4.0 GB)
00:00:01.807690 VRamSize <integer> = 0x0000000003000000 (50 331 648, 48 MB)
You allocated RAM you don't have. Reduce VM RAM to 2048MB. Increase graphics RAM to 128MB.
00:00:01.807400 NumCPUs <integer> = 0x0000000000000001 (1)
...
00:00:01.978634 CPUM: Physical host cores: 4
Modern Windows will perform poorly if only given one core. Your host has capacity, so set this to 2.
00:00:22.612411 Display::i_handleDisplayResize: uScreenId=0 pvVRAM=0000000119f23000 w=2560 h=1290 bpp=32 cbLine=0x2800 flags=0x1 origin=0,0
That's a large display size. Each frame would require 13.2MB, so 48MB VRAM was definitely low. You might consider reducing screen dimensions to half of this, but with a x2 scale factor.
00:00:02.493995 GUI: 2D video acceleration is disabled
00:00:01.807685 3DEnabled <integer> = 0x0000000000000000 (0)
Both 2D and 3D acceleration is disabled. Depending on what you use the VM for, you might find it beneficial to enable 2D acceleration, or 2D+3D acceleration. With 3D acceleration enabled you can also increase VRAM to 256MB.
00:00:01.951890 AHCI: LUN#0: disk, PCHS=16383/16/63, total number of sectors 52428800
That's a hard disk size of around 25GB. A tad small for Win7. Be aware that if the drive is congested then that can cause fragmentation and lowered drive performance: though this is not so much a problem is the drive is located on a host SSD. Of course it is also easier to run out of space, which is what your warning messages may be about.
That should be enough for you to look at for now.