It depends as much on the burner as it does the disc. I've recently been using Sony DVD-R discs burned in my HP laptop's internal drive and they run fine on my 39001, my 75001, and my girlfriend's 75001 (of the latter two, hers is more iffy than mine, it won't read dual-layer discs of any sort). This is also true for an older HP desktop I have sitting around here, and two previous HP laptops. I also have an external Memorex DVD burner which I have yet to successfully burn a PS2 game with, regardless of media. In the various HP drives, I've also used several brands of disc, including a few Memorex, and a few "house brand" discs from Office Depot back in 2007/8. I've always preferred DVD-R over DVD+R, I've gotten more consistent results with them. I also haven't noticed any speed issues on any of these PS2s, although I don't use a ton of burnt discs as I prefer the HDD, but I've backed up several of my girlfriend's discs for her and she hasn't noticed any problems either.
Chip-free homebrew <3
SCPH-39001, FMCB 1.8c, NA+250GB HDD
SCPH-75001, FMCB 1.8c
GSM 0.36 + OPL r639 = Gaming bliss ^_^