diff --git a/mirai-core/src/commonMain/kotlin/net.mamoe.mirai/utils/io/DebugUtil.kt b/mirai-core/src/commonMain/kotlin/net.mamoe.mirai/utils/io/DebugUtil.kt
index 151b55b00..4c25f58a2 100644
--- a/mirai-core/src/commonMain/kotlin/net.mamoe.mirai/utils/io/DebugUtil.kt
+++ b/mirai-core/src/commonMain/kotlin/net.mamoe.mirai/utils/io/DebugUtil.kt
@@ -2,9 +2,7 @@ package net.mamoe.mirai.utils.io
 
 import kotlinx.io.core.*
 import kotlinx.io.pool.useInstance
-import net.mamoe.mirai.utils.DefaultLogger
-import net.mamoe.mirai.utils.MiraiLogger
-import net.mamoe.mirai.utils.withSwitch
+import net.mamoe.mirai.utils.*
 import kotlin.contracts.ExperimentalContracts
 import kotlin.contracts.InvocationKind
 import kotlin.contracts.contract
@@ -14,18 +12,22 @@ object DebugLogger : MiraiLogger by DefaultLogger("Packet Debug").withSwitch()
 
 fun Throwable.logStacktrace(message: String? = null) = DebugLogger.error(message, this)
 
+@MiraiDebugAPI("Low efficiency.")
 fun debugPrintln(any: Any?) = DebugLogger.debug(any)
 
+@MiraiDebugAPI("Low efficiency.")
 fun String.debugPrint(name: String): String {
     DebugLogger.debug("$name=$this")
     return this
 }
 
+@MiraiDebugAPI("Low efficiency.")
 fun ByteArray.debugPrint(name: String): ByteArray {
     DebugLogger.debug(name + "=" + this.toUHexString())
     return this
 }
 
+@MiraiDebugAPI("Low efficiency.")
 fun IoBuffer.debugPrint(name: String): IoBuffer {
     ByteArrayPool.useInstance {
         val count = this.readAvailable(it)
@@ -34,6 +36,7 @@ fun IoBuffer.debugPrint(name: String): IoBuffer {
     }
 }
 
+@MiraiDebugAPI("Low efficiency.")
 inline fun IoBuffer.debugCopyUse(block: IoBuffer.() -> Unit): IoBuffer {
     ByteArrayPool.useInstance {
         val count = this.readAvailable(it)
@@ -42,10 +45,12 @@ inline fun IoBuffer.debugCopyUse(block: IoBuffer.() -> Unit): IoBuffer {
     }
 }
 
+@MiraiDebugAPI("Low efficiency.")
 fun Input.debugDiscardExact(n: Number, name: String = "") {
     DebugLogger.debug("Discarded($n) $name=" + this.readBytes(n.toInt()).toUHexString())
 }
 
+@MiraiDebugAPI("Low efficiency.")
 fun ByteReadPacket.debugPrint(name: String = ""): ByteReadPacket {
     ByteArrayPool.useInstance {
         val count = this.readAvailable(it)
@@ -59,7 +64,7 @@ fun ByteReadPacket.debugPrint(name: String = ""): ByteReadPacket {
  *
  * 此方法非常低效. 请仅在测试环境使用.
  */
-@MiraiDebugAPI
+@MiraiDebugAPI("Low efficiency")
 @UseExperimental(ExperimentalContracts::class)
 inline fun <R> Input.debugIfFail(name: String = "", onFail: (ByteArray) -> ByteReadPacket = { it.toReadPacket() }, block: ByteReadPacket.() -> R): R {
     contract {