my shop https://uask.biz has 180k products 2 languages, usual hosting plan 4$/month (not VPS), data is updating every hour. Opencart is really cool engine.
If you see such error please edit admin/view/template/common/column_left.tpl on line 5
find
title="<?php echo $username; ?>"
and change to
title="<?php echo $firstname; ?> <?php echo $lastname; ?>"
to avoid the error when you add an image to opencart user in admin panel.