Despite upgrading server bandwidth from 10Mbps to 100Mbps or even higher, website access speeds remain slow. Issues such as long page loading delays, slow image loading, video playback stuttering, and sluggish interface responses persist, leading one to mistakenly believe that the bandwidth upgrade was ineffective. In reality, website access speed is not determined solely by bandwidth; it's a combination of factors including network connectivity, server performance, application architecture, front-end resources, CDN, DNS resolution, and even the network environment of the user's location. Insufficient bandwidth certainly slows down speeds, but even upgrading to very high bandwidth cannot solve other structural problems.
Bandwidth primarily affects "concurrent transmission capacity" and "single file download speed," but it does not change network latency. The network distance and physical links between Japan and mainland China, Southeast Asia, Europe, and the Americas do not shorten with bandwidth upgrades. If a user accessing your website needs to traverse 8-12 routing nodes, and some of these nodes are congested or have unstable quality, then even 1Gbps bandwidth will not improve latency. Latency is often a major factor causing slow and choppy page experiences, especially when API requests, database queries, and dynamic page rendering are involved. The cumulative effect of latency can lead to noticeable stuttering. Therefore, the primary reason why speeds remain slow even after upgrading bandwidth on Japanese servers is that cross-border link latency itself cannot be resolved by bandwidth expansion.
Another important factor affecting access speed is international link congestion. Although the local bandwidth of Japanese servers is sufficient, users need to access the network through cross-border networks. For example, users from mainland China typically need to go through CN2, BGP relay, backbone network exit, and then through a Japanese local ISP. If your Japanese VPS uses a cheap, standard line, packet loss and congestion are very likely to occur during peak hours, resulting in significant latency fluctuations. Even if you upgrade the bandwidth, the speed for cross-border visitors still depends on the link conditions, not the bandwidth itself. Therefore, bandwidth expansion cannot solve the problem of poor link quality, especially when the link is poor in areas with concentrated user access.
Another common reason for slow access after bandwidth upgrades is insufficient server performance. For example, CPU processing bottlenecks, insufficient memory leading to swapping, excessive disk I/O, and insufficient web service threads can all slow down user access speeds. Bandwidth improves data transmission capacity, but server processing of web page content, generation of dynamic pages, database queries, script execution, and file compression all rely on CPU and memory. If the server load is already high, user access speed will not improve simply by increasing bandwidth.
If the CPU is frequently running at full capacity, disk I/O is approaching 100%, and insufficient memory is causing excessive swapping, then the problem is clearly not with bandwidth, but with the system resources themselves.
An unreasonable front-end resource structure is also a significant factor contributing to slow speeds. Many websites have huge images, no compression enabled, and load large amounts of JS and CSS on the homepage, resulting in a large amount of resources piling up during the initial load phase, severely slowing down access speeds. In this case, even with sufficient bandwidth, users will wait a long time due to the large number of resources. For example, a 5MB image theoretically downloads in about 0.4 seconds with 100Mbps bandwidth, but if the user's connection is congested, the server load is high, and compression is not enabled, the actual speed may be far lower than the theoretical value. If a website contains a dozen or so uncompressed images, the speed issue will be even more pronounced.
To optimize front-end resources, gzip compression can be enabled in Nginx to reduce transmission size. These configurations can significantly reduce the size of text files, thereby lowering loading time.
On the other hand, many users overlook the access latency caused by DNS resolution. Excessive DNS resolution time, poor DNS provider quality, and unnecessary redirects in DNS records can all slow down website loading. In particular, some Japanese servers use DNS servers that are not very friendly to users in China, often resulting in high latency and slow resolution. If the resolution time exceeds 200ms, it indicates that the DNS itself is the bottleneck, not the bandwidth.
The most common real reason for slow access speeds after bandwidth upgrades is actually the lack of a CDN. No matter how much server bandwidth there is, the farther the resource is from the user, the slower the transmission speed. The value of a CDN lies in caching resources near the user, reducing cross-border access. For example, when a Chinese user accesses a Japanese server, if all images, videos, and static files need to be fetched from Japan, the speed will inevitably be slow. Enabling a CDN allows users to retrieve static resources from local nodes, significantly reducing cross-border traffic. For sites with many images, enabling a CDN is the most direct way to improve access speed, bar none.
Another easily overlooked factor is improper web service configuration. For example, too few Nginx worker processes, disabled reverse proxy caching, and improper Keepalive settings can all impact speed. Some sites require every request to be processed by the backend without any caching optimization; this architecture easily leads to increased latency under high traffic. You can check the Nginx connection count using commands; if the number is close to the limit, you should increase `worker_connections` or add a caching strategy.
For PHP, Node.js, or Python websites, low backend execution efficiency, frequent slow database queries, and excessive ORM queries can also cause access bottlenecks. Bandwidth expansion cannot solve application-layer performance issues; therefore, APM tools such as OpenTelemetry, SkyWalking, or New Relic should be used to analyze application performance bottlenecks.
Furthermore, while some Japanese servers boast high advertised local bandwidth, their actual external bandwidth is only high-speed within Japan, limiting international access due to limited outbound bandwidth. For example, some low-priced VPSs offer only a "1Gbps domestic, 10Mbps international" configuration, resulting in fast speeds within Japan but extremely slow cross-border access. Upgrading bandwidth in this case essentially upgrades domestic bandwidth, while international outbound bandwidth may remain unchanged, thus failing to improve access speed.
After ruling out these possible factors, you'll find that bandwidth upgrades are only one aspect, and slow access speeds are usually the result of multiple factors working together. Bandwidth itself is not the only bottleneck. To truly resolve slow access speeds, a comprehensive approach is needed, addressing issues such as network connectivity, caching, architecture, front-end optimization, server performance, CDN, and DNS.
